US9161771B2 - Medical instrument with snake wrist structure - Google Patents

Abstract

A medical instrument includes a snake wrist structure further including: a first joint disk having a first rim having a first tooth slot and a first toothed gear with the first tooth slot opposite the first toothed gear along the first rim; and a first strut having a first slot bearing and a first hole bearing connected by a first connection strut with the first slot bearing in the first tooth slot.

Description

TECHNICAL FIELD

The present invention relates generally to a medical instrument, and more particularly to a medical instrument for holding a mechanism attached therein in different positions.

BACKGROUND ART

Modern tools and manipulating instruments, including instruments with jaws for performing surgical operations, such as cutting, grasping and holding, are providing increasing levels of functionality and strength to support modern needs including applications in minimally invasive and micro-surgery. However, the tools available for positioning the manipulating instruments are not efficient and often lack precision.

As instruments become smaller and stronger with the growth of material science and manufacturing, new and old paradigms begin to take advantage of the improvements. There are many technological solutions to take advantage of smaller and stronger tools. One existing approach is to use smaller tools to perform micro-surgery or minimally invasive surgery.

Often, the methods of operating the tools for performing micro-surgery are not intuitive and require special training and attention of the user. Furthermore, the tools are often not efficient in applying the correct amount of force and lack the required degree of maneuverability needed to controllably navigate complex anatomy during surgical procedures.

The need to reduce costs, improve efficiencies and performance, and meet competitive pressures adds an even greater urgency to the critical necessity for finding answers to these problems. However, solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art. Thus, a need still remains for manipulating device with a flexible jaw and wrist mechanism.

DISCLOSURE OF THE INVENTION

The present invention provides a medical instrument including a snake wrist structure further including a first joint disk having a first rim having a first tooth slot and a first toothed gear with the first tooth slot opposite the first toothed gear along the first rim; and a first strut having a first slot bearing and a first hole bearing connected by a first connection link with the first slot bearing in the first tooth slot.

Certain embodiments of the invention have other steps or elements in addition to or in place of those mentioned above. The steps or elements will become apparent to those skilled in the art from a reading of the following detailed description when taken with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a medical instrument with a snake wrist structure in a first embodiment of the present invention.

FIG. 2 is an isometric view of the snake wrist structure in a second embodiment.

FIG. 3 is an isometric of the snake wrist structure in a flexed position in a second embodiment.

FIG. 4 is an exploded side view of the snake wrist structure in a second embodiment.

FIG. 5 is an example of the first strut in a second embodiment.

FIG. 6 is an exploded view of the snake wrist structure in a second embodiment.

FIG. 7 is a cutaway view of the snake wrist structure in a flexed position in a second embodiment.

FIG. 8 is an isometric view of the snake wrist structure in an unflexed position in a second embodiment.

FIG. 9 is a front view of the snake wrist structure in a second embodiment.

FIG. 10 is an isometric view of the first joint disk.

FIG. 11 is a top view of the first joint disk in a second embodiment.

FIG. 12 is an isometric view of the bottom of the first joint disk in a second embodiment.

FIG. 13A is a first isometric view of the snake wrist structure in a third embodiment.

FIG. 13B is a second isometric view of the snake wrist structure in a third embodiment.

FIG. 14 is a side view of the snake wrist structure in an unflexed position in a third embodiment.

FIG. 15 is an exploded view of the snake wrist structure in a third embodiment.

FIG. 16 is an isometric view of the first joint disk in a third embodiment.

FIG. 17 is a side view of the bottom of the first joint disk in a third embodiment.

FIG. 18 is an isometric view of the bottom of the first joint disk in a third embodiment.

FIG. 19A is a first isometric view of the snake wrist structure in a fourth embodiment.

FIG. 19B is a second isometric view of the snake wrist structure in a fourth embodiment.

FIG. 20 is an isometric view of the snake wrist structure in a flexed position in a fourth embodiment.

FIG. 21 is an exploded view of the snake wrist structure in a fourth embodiment.

FIG. 22 is an isometric view of the bottom of the first joint disk in a fourth embodiment.

FIG. 23 is a side and front view of the first strut.

FIG. 24 is an isometric view of the first joint disk in a fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

The following embodiments are described in sufficient detail to enable those skilled in the art to make and use the invention. It is to be understood that other embodiments would be evident based on the present disclosure, and that system, process, or mechanical changes may be made without departing from the scope of the present invention.

In the following description, numerous specific details are given to provide a thorough understanding of the invention. However, it will be apparent that the invention may be practiced without these specific details. In order to avoid obscuring the present invention, some well-known devices, instrument configurations, and process steps are not disclosed in detail.

For expository purposes, the term “horizontal” as used herein can be the horizontal direction seen when viewing the drawing as indicated by the figure designation of “FIG.”. The term “vertical” refers to a direction perpendicular to the horizontal as just defined. Terms, such as “above”, “below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, are defined with respect to the horizontal, as shown in the figures. The term “directly on” means there is direct contact with no intervening element between the elements described.

Also, in the following description, connected and coupled are used to describe a relationship between two members. The term “connected” means that the two members are physically and directly joined to each other.

Different members can be connected in variety of ways. For example, different members can be connected by being formed adjacent to each other, such as through molding or carving. Also, for example, different members can be connected by being attached together, such as through adhesives, fasteners, welds, or brazing.

The term “coupled” means that the two members are physically linked through one or more other members. The phrases “reciprocating motion” and “reciprocating movement” are defined to describe a repetitive up-and-down or back-and-forth motion. The phrases “distal” and “proximal” are defined to respectively indicate the directions designated by the related arrows inFIG. 1 or along the path of connectivity between the point where the instrument couples to the robot arm (proximal) and the instrument tip that contacts surgical patient tissue (distal).

The drawings showing embodiments of the system are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown exaggerated in the drawing FIGs. Similarly, although the views in the drawings for ease of description generally show similar orientations, this depiction in the FIGs. is arbitrary for the most part. Generally, the invention can be operated in any orientation.

Referring now toFIG. 1, therein is shown amedical instrument100 with asnake wrist structure110 in a first embodiment of the present invention. Thesnake wrist structure110 is a segmented member that bends or provides multi-axis movement to change the relative position and orientation of a member attached thereon. The term “segmented” is defined as a structure including one or more individual segments or links. Thesnake wrist structure110 is also supported by anotherconnection member111 attached thereon.

Theconnection member111 is defined as a structural element that can be physically and directly joined to thesnake wrist structure110. Theconnection member111 can include a variety of elements including a stationary member, a moveable member, a rotating member, an articulating member, a fixed member, or a combination thereof. Theconnection member111 can be connected on either side of thesnake wrist structure110.

For example, thesnake wrist structure110 can be connected to the stationary member on one side and the moveable member on the opposite side. The stationary member can hold thesnake wrist structure110 in position and thesnake wrist structure110 can be manipulated to move and position the moveable member.

For a more specific example, thesnake wrist structure110 can have a mechanical awl attached to one side and a camera on the other side. The mechanical arm can position thesnake wrist structure110 and the camera in place. Thesnake wrist structure110 can be manipulated to present different angles, orientations, and views for the camera from the given location.

Themedical instrument100 can include aproximal end102 and adistal end104. For example, themedical instrument100 can include thesnake wrist structure110 near thedistal end104, atube112 with actuating members114 (shown in a cutaway view oftube112 inFIG. 1), and anactuator system118 at theproximal end102. Themedical instrument100 can include a tool or sensory mechanism at the distal end, such as ajaw mechanism122, camera, probe, light, tube, cutter, or a combination thereof.

In a further example, thejaw mechanism122 can be at thedistal end104 of themedical instrument100. Thesnake wrist structure110 can be connected to thejaw mechanism122. Thesnake wrist structure110 can have thetube112 attached on the other side. Thesnake wrist structure110 can also be coupled to theactuator system118 through theactuating members114. Thejaw mechanism122 can be analogous to a human hand, and thesnake wrist structure110 can be analogous to a human wrist. Thejaw mechanism122 can be a mechanical assembly, such as a gripper or a cutter.

Thesnake wrist structure110 is shown having a cylindrical configuration having acentral axis119 that extends through the center of thesnake wrist structure110. The cylindrical configuration eliminates sharp edges and allows thesnake wrist structure110 and thejaw mechanism122 to project into tight spaces and navigate complex anatomy.

Thetube112 holds thesnake wrist structure110 at a location in space. For example, thetube112 can be straight tube of a medical instrument. For illustrative purposes, thetube112 is shown as a hollow cylindrical member encasing theactuating members114 within thetube112. However, it is understood that thetube112 can be different and have various cross-sectional shapes, or be solid and have externally theactuating members114.

Thesnake wrist structure110 can be attached at thedistal end104 of thetube112 and theactuator system118 at theproximal end102. Generally, thejaw mechanism122 is attached at thedistal end104.

Theactuator system118 exerts forces coupled by the actuatingmembers114 to bend thesnake wrist structure110 and to actuate thejaw mechanism122. The actuatingmembers114, for example, can be a rod or cable or cable and pulley system that is pushed or pulled to bend thesnake wrist structure110 along the direction of applied force. Theactuator system118 can also be coupled through the actuatingmembers114 to convey the forces to cause rotating reciprocation motion of thejaw mechanism122.

Theactuator system118 may include or may be coupled to electrical, hydraulic, or pneumatic power systems to generate the applied forces. Acontrol system120 can be coupled to theactuator system118 for controlling the amount of applied forces and motion for thejaw mechanism122 and awrist mechanism124. Thecontrol system120 is a mechanism that can control the operation of thejaw mechanism122. For example, thecontrol system120 can be a computer and motor assembly or an assembly of handles, gears, and levers.

Referring now toFIG. 2, therein is shown an isometric view of thesnake wrist structure110 in a second embodiment. Thesnake wrist structure110 is in an unflexed configuration.

Thesnake wrist structure110 can include afirst locking member201 connected to a firstjoint disk202. Thefirst locking member201 is defined as a structural element used to connect the firstjoint disk202 to another member. Thefirst locking member201 can be a cylindrical tube with an outer diameter approximately equal to a diameter of a firstinner opening222 of the firstjoint disk202. Thefirst locking member201 forms a tight fit with the firstinner opening222 when connected to the firstjoint disk202.

The firstjoint disk202 is defined as a structural element that can be coupled to other similar joint disk elements to form thesnake wrist structure110. The firstjoint disk202 can be a circular structure with a single toothed gear and a single tooth slot along the outside diameter of the firstjoint disk202 for forming an articulating joint.

Thesnake wrist structure110 can include the firstjoint disk202. The firstjoint disk202 can include a set of thefirst alignment keys206, a firstangled surface208, afirst rim209, afirst tooth slot210, and a firsttoothed gear212.

The firstjoint disk202 can include the firstinner opening222 in the center of the firstjoint disk202. The firstinner opening222 is defined as the central unobstructed through lumen of the joint disk. A lumen is defined as an internal cavity or opening in a cylindrical structure. The inner openings of the coupled disks of thesnake wrist structure110 can form asnake wrist lumen290 in thesnake wrist structure110.

Thesnake wrist lumen290 is defined as a channel in thesnake wrist structure110 that can be used to pass mechanical, electrical, or optical cables or other control tubes. Thesnake wrist lumen290 can also be a through lumen for providing fluid or gas delivery or extraction, or for use as a through lumen in the instrument to allow for the passage of secondary smaller diameter surgical tools through the snake joint assembly such as a biopsy needle, grasper, or laser fiber.

The firstjoint disk202 can include thefirst alignment keys206 around the bottom of the firstjoint disk202. Thefirst alignment keys206 are defined as structures for connecting the firstjoint disk202 with theconnection member111 ofFIG. 1 in a fixed orientation and to prevent rotation of the firstjoint disk202 relative to theconnection member111. Thefirst alignment keys206 are positioned around the bottom circumference of the firstjoint disk202 distributed 90 degrees apart from one another.

Thefirst alignment keys206 can have a firstalignment key tab203 and a first alignmentkey hole205. The firstalignment key tab203 can be an extended structure used to interlock with the first alignmentkey hole205 of another element. The first alignmentkey hole205 can be a hole in the firstjoint disk202 where the firstalignment key tab203 of another element can fit into to lock the firstjoint disk202 in place. Thefirst alignment keys206 can be connected to the alignment keys of another disk whereby the firstalignment key tab203 are inserted in the first alignmentkey hole205 of another disk.

The firstjoint disk202 can include thefirst tooth slot210 in thefirst rim209 of the firstjoint disk202. Thefirst tooth slot210 is defined as an opening acting as a receiver for a toothed gear to form a pivoting joint or hinge structure. Thefirst tooth slot210 can be as a concave opening in thefirst rim209 of the firstjoint disk202. Thefirst tooth slot210 can receive a secondtoothed gear242 to form a pivoting joint or hinge. A pivoting joint is a connection between two rigid elements where one element can pivot or rotate relative to the other element.

Thefirst rim209 is defined as a structural element extending around the circumference of the top of the firstjoint disk202. Thefirst rim209 can include thefirst tooth slot210, the firsttoothed gear212, and the firstangled surface208.

The firstjoint disk202 can include the firsttoothed gear212 on the opposite side of thefirst rim209 across from thefirst tooth slot210. The firsttoothed gear212 can be a structure that extends from thefirst rim209 of the firstjoint disk202 to form a pivoting joint or hinge when inserted into a matching slot. The firsttoothed gear212 can be a convex shape for guiding the motion of the firstjoint disk202.

As an example, the firstjoint disk202 can include the firstangled surface208 around both sides thefirst rim209 of the firstjoint disk202 between the firsttoothed gear212 to thefirst tooth slot210. The firstangled surface208 can be a structural element of the firstjoint disk202 used as a mechanical stop to limit the range of motion of the firstjoint disk202 or other elements. The firstangled surface208 can extend in a semi-circular arc in a downward direction from the base of the firsttoothed gear212 and top of thefirst tooth slot210 reaching a maximum depth midway between the firsttoothed gear212 and thefirst tooth slot210.

In another example, the firstangled surface208 can form an angle approximately of 22.5 degrees below a plane orthogonal to thecentral axis119 ofFIG. 1 whereby the first joint can be articulated to a maximum angle 45 degrees from thecentral axis119.

It has been discovered that the present invention provides a 50% reduction in the moment arm for the cable force component. At 45 degrees, the moment arm for the cable force component contributing to joint torque is cut in half. Further range of motion is technically possible but comes at the cost of rapidly diminishing joint torque and increased risk of cable damage due to the amount of required flex.

The firstjoint disk202 can include a set of first cable holes214. The first cable holes214 are defined as opening for passing joint control cables through joint disks. The first cable holes214 can be openings extending through the firstjoint disk202 to provide access for the joint control cables (not shown). The joint control cables are defined as cables that are used to control the flexing of joints in thesnake wrist structure110.

The firstjoint disk202 can include a set offirst cable cutouts216 around the first cable holes214 on the same side of the firstjoint disk202 as the firstangled surface208. Thefirst cable cutouts216 are defined as beveled areas around the first cable holes214 to accommodate motion of the joint control cables when thesnake wrist structure110 is flexed. Thesnake wrist structure110 can include a secondjoint disk232. The secondjoint disk232 is defined as a structural element that can be coupled to other joint disk elements to form thesnake wrist structure110. The secondjoint disk232 can be a duplicate of the firstjoint disk202 in an inverted and rotated position. The secondjoint disk232 is mounted over the firstjoint disk202 in an inverted position and rotated 180 degrees. The firstjoint disk202 can be connected to the secondjoint disk232 to form an articulating joint.

The secondjoint disk232 can have the same configuration as the firstjoint disk202. The secondjoint disk232 can include the secondtoothed gear242, a secondangled surface238, asecond rim235, a set ofsecond alignment keys236, and asecond bearing hole254.

The secondjoint disk232 can include the secondtoothed gear242. The secondtoothed gear242 can be a structure that extends from thesecond rim235 of the secondjoint disk232 to form a pivoting joint or hinge when inserted into a matching slot. The secondjoint disk232 can be mounted over the firstjoint disk202 whereby the secondtoothed gear242 is over thefirst tooth slot210 of the firstjoint disk202. The secondtoothed gear242 can be inserted into thefirst tooth slot210 of the firstjoint disk202. The secondtoothed gear242 can be a single toothed gear extending from thesecond rim235 of the secondjoint disk232. The secondtoothed gear242 can have a convex shape for guiding the motion of the secondjoint disk232.

The secondjoint disk232 can include thesecond alignment keys236. Thesecond alignment keys236 are on the side of the secondjoint disk232 opposite from the secondtoothed gear242. Thesecond alignment keys236 are defined as structures for connecting the secondjoint disk232 with another element in a fixed orientation and to prevent rotation of the secondjoint disk232 relative to the other element. For example, the other element can be another joint disk, a mounting surface, an extension element, or a combination thereof.

The secondjoint disk232 can include the secondangled surface238 around both sides of thesecond rim235 of the secondjoint disk232. The secondangled surface238 extends in a semi-circular arc in a downward direction from the base of the secondtoothed gear242 and the point opposite the secondtoothed gear242 reaching a maximum depth midway between the secondtoothed gear242 and point opposite the secondtoothed gear242. For example, the secondangled surface238 can be formed at an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

The secondjoint disk232 can be coupled to the firstjoint disk202 by afirst strut226 and asecond strut228. Thefirst strut226 can include a first hole bearing227 and a first slot bearing225.

The first hole bearing227 can be a structural element forming an axis of rotation for the secondjoint disk232. The first hole bearing227 can be a cylindrical element that can bear loads.

The first slot bearing225 can be a structural element forming an axis of rotation for the firstjoint disk202. The first slot bearing225 can be a cylindrical element that can bear loads.

Thefirst strut226 can attach to the secondjoint disk232 with the first hole bearing227 inserted into thesecond bearing hole254. Thefirst strut226 can attach to the firstjoint disk202 with the first slot bearing225 inserted into thefirst tooth slot210.

Thesnake wrist structure110 can include a thirdjoint disk262. The thirdjoint disk262 can have the same configuration as the firstjoint disk202 and the secondjoint disk232. The thirdjoint disk262 is mounted over and directly in contact with the secondjoint disk232.

The thirdjoint disk262 can include a set ofthird alignment keys266 spaced evenly around the circumference of the bottom of the thirdjoint disk262. Thethird alignment keys266 are defined as structures for connecting the thirdjoint disk262 with another element in a fixed orientation and to prevent rotation of the thirdjoint disk262 relative to the other element.

The thirdjoint disk262 can include athird tooth slot270 and a thirdtoothed gear272. The thirdjoint disk262 is mounted over the secondjoint disk232. The thirdjoint disk262 can be in a variety of orientations in relation to the secondjoint disk232.

The thirdjoint disk262 can include a thirdangled surface268. The thirdangled surface268 extends in a semi-circular arc in an downward direction from the base of the thirdtoothed gear272 and thethird tooth slot270 reaching a maximum depth midway between the thirdtoothed gear272 and thethird tooth slot270. For example, the thirdangled surface268 can be formed at an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

The thirdjoint disk262 is connected to the secondjoint disk232 whereby thesecond alignment keys236 are interlocked with thethird alignment keys266. Interlocking can be connecting two elements to prevent rotation. Interlocking can occur when the firstalignment key tab203 of the secondjoint disk232 are in the first alignmentkey hole205 of the thirdjoint disk262.

The thirdjoint disk262 can be connected to the secondjoint disk232 with an interlocking structure. The interlocking structure can include thethird alignment keys266 interlocked with thesecond alignment keys236. The interlocking structure can hold the thirdjoint disk262 and the secondjoint disk232 in a fixed orientation to one another.

For example, the third disk joint can be rotated whereby thethird tooth slot270 and the thirdtoothed gear272 are at right angles to the secondjoint disk232. Thethird tooth slot270 and the thirdtoothed gear272 are on the opposite side of the thirdjoint disk262 from the secondjoint disk232.

In another example, the thirdjoint disk262 can be rotated 180 degrees around thecentral axis119 and mounted on the secondjoint disk232. By mounting the thirdjoint disk262 at a 180 degree angle to the secondjoint disk232, thesnake wrist structure110 can flex further around the bending axis of the firstjoint disk202 and the secondjoint disk232.

Thesnake wrist structure110 can include ajoint knuckle295. Thejoint knuckle295 can be formed by connecting the firstjoint disk202 to the secondjoint disk232 with thefirst strut226 and thesecond strut228. Thejoint knuckle295 can have an interconnect structure on the proximal and distal ends to facilitate connecting to afurther connection member111 ofFIG. 1.

Thesnake wrist structure110 has a firsttransverse dimension296 and a secondtransverse dimension298 along a plane orthogonal to thecentral axis119. Thecentral axis119 is defined as an axis that extends along the center of thesnake wrist structure110 in an unflexed configuration. The firsttransverse dimension296 and the secondtransverse dimension298 are shown to be the same but do not need to be and may be adjusted based on the geometry of thesnake wrist structure110. In the case in which they are equal, thesnake wrist structure110 may be circular in cross section as illustrated inFIG. 2. As an example, the firsttransverse dimension296 and the secondtransverse dimension298 are shown to be along directions perpendicular to each other but does not necessarily required to be perpendicular.

Thesnake wrist structure110 can include a variety of configuration examples. For example, thejoint knuckle295 can be a single degree of freedom joint subassembly that consists of two identical struts and two identical joint disks that combine to provide ±45 degrees of motion about the joint axis.

In another example, a “single degree of freedom joint” can be constructed by joining two identical pairs of disk-and-strut where each disk has a strut attached to the disk by mating the strut's tooth-side bearing to the tooth-side bearing on the disk. Once these two pairs are built, they are joined together aligned axially but rotated 180 degrees about the central axis of the disk whereby they mesh in a complimentary fashion. This can allow each strut's slot-side bearing surface to be mated with a slot bearing-surface on each disk.

In yet another example, the “single degree of freedom joint” can be used as a repeating unit where identical copies are stacked axially along the central axis of the instrument shaft with each subsequent joint oriented whereby its pivot axis is parallel to the previous joint in the chain or rotated 90 degrees to the previous joint axis. This can allow for a snake wrist structure with multiple degrees of freedom and a range of motion in each degree of freedom in increments of 45 degrees based on how many joints are stacked with the same orientation.

In still another example, when the single degree of freedom subassemblies are stacked together, interlocking features in adjacent identical subassemblies lock the struts and disks together whereby the struts cannot be removed from the disk, even in the event of a cable failure.

Referring now toFIG. 3 therein is shown an isometric of thesnake wrist structure110 in a flexed position in a second embodiment. Thesnake wrist structure110 can include thefirst locking member201 and the firstjoint disk202.

Thesnake wrist structure110 includes thefirst locking member201 connected to the firstjoint disk202. Thefirst locking member201 forms a tight fit with the firstinner opening222 when connected to the firstjoint disk202.

The firstjoint disk202 can include the firstinner opening222. The firstinner opening222 can be an opening in acentral portion302 of the firstjoint disk202. Thecentral portion302 is defined as the interior part of the firstjoint disk202 surrounding thecentral axis119 ofFIG. 1.

The firstjoint disk202 can includefirst alignment keys206 around the bottom of the circumference of the firstjoint disk202. Thefirst alignment keys206 are distributed 90 degrees apart from one another around the bottom circumference of the firstjoint disk202. Thefirst alignment keys206 have the firstalignment key tab203 and the first alignmentkey hole205. Thefirst alignment keys206 can be connected to the alignment keys of another disk whereby the firstalignment key tab203 are inserted in the first alignmentkey hole205 of another disk.

The firstjoint disk202 can include thefirst tooth slot210 on thefirst rim209 of the firstjoint disk202. The firstjoint disk202 can include the firsttoothed gear212 on the opposite side of thefirst rim209 across from thefirst tooth slot210.

The firstjoint disk202 can include the firstangled surface208 around both sides thefirst rim209 of the firstjoint disk202 between the firsttoothed gear212 to thefirst tooth slot210. The firstangled surface208 extends in downward directions from the base of the firsttoothed gear212 and top of thefirst tooth slot210 reaching a maximum depth midway between the firsttoothed gear212 and thefirst tooth slot210. The firstangled surface208 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

Thesnake wrist structure110 can include the secondjoint disk232. The secondjoint disk232 can have the same configuration as the firstjoint disk202. The secondjoint disk232 is mounted over the firstjoint disk202 in an inverted position and rotated 180 degrees.

The secondjoint disk232 can include asecond tooth slot340 and the secondtoothed gear242. The secondjoint disk232 is mounted over the firstjoint disk202 whereby thesecond tooth slot340 is over the firsttoothed gear212 and the secondtoothed gear242 is over thefirst tooth slot210 of the firstjoint disk202. The secondtoothed gear242 can be inserted into thefirst tooth slot210 of the firstjoint disk202. The firsttoothed gear212 of the firstjoint disk202 can be inserted into thesecond tooth slot340.

The secondjoint disk232 can include thesecond alignment keys236. Thesecond alignment keys236 are on the side of the secondjoint disk232 opposite from thesecond tooth slot340 and the secondtoothed gear242.

The secondjoint disk232 can include the secondangled surface238 around both sides of thesecond rim235 ofFIG. 2 of the secondjoint disk232 between the secondtoothed gear242 to thesecond tooth slot340. The secondangled surface238 extends in downward directions from the base of the secondtoothed gear242 and top of thesecond tooth slot340 reaching a maximum depth midway between the secondtoothed gear242 and thesecond tooth slot340. The secondangled surface238 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

The secondjoint disk232 can be coupled to the firstjoint disk202 by afirst strut226 and thesecond strut228. Thefirst strut226 can include a first hole bearing227 and a first slot bearing225.

Thefirst strut226 can attach to the secondjoint disk232 with the first hole bearing227 inserted into thesecond bearing hole254. Thefirst strut226 can attach to the firstjoint disk202 with the first slot bearing225 inserted into thefirst tooth slot210.

The secondjoint disk232 can be in a flexed position where the secondjoint disk232 is flexed around the bending axis between the firstjoint disk202 and the secondjoint disk232 and the secondangled surface238 is closer to the firstangled surface208 on one side of thesnake wrist structure110 and further apart on the opposite side of thesnake wrist structure110.

Thesnake wrist structure110 can include the thirdjoint disk262. The thirdjoint disk262 can have the same configuration as the firstjoint disk202 and the secondjoint disk232. The thirdjoint disk262 is mounted over and directly in contact with the secondjoint disk232.

The thirdjoint disk262 can include thethird alignment keys266 spaced evenly around the circumference of the bottom of the thirdjoint disk262. The thirdjoint disk262 is connected to the secondjoint disk232 whereby thesecond alignment keys236 are interlocked with thethird alignment keys266. Interlocking can be connecting two elements together to prevent rotation.

The thirdjoint disk262 can include thethird tooth slot270 and the thirdtoothed gear272. The thirdjoint disk262 is mounted over the secondjoint disk232 whereby thethird tooth slot270 and the thirdtoothed gear272 are rotated 90 degrees away from thesecond tooth slot340 and the secondtoothed gear242. Thethird tooth slot270 and the thirdtoothed gear272 are on the opposite side of the thirdjoint disk262 from the secondjoint disk232.

Thesnake wrist structure110 can flex in a variety of ways with different degrees of freedom. For example, when the secondjoint disk232 is flexed toward one side of thesnake wrist structure110, the angular degree of flex is limited by the geometry of the firstangled surface208 and the secondangled surface238. The range of motion of the secondjoint disk232 is limited by when the firstangled surface208 and the secondangled surface238 meet and prevent further motion. For example, the secondjoint disk232 can only flex a maximum of 45 degrees if when the firstangled surface208 and the secondangled surface238 each form a 22.5 degree angle from the horizontal plane.

The firstjoint disk202, the secondjoint disk232, and the thirdjoint disk262 can all have the same configuration. For example, the secondjoint disk232 and the thirdjoint disk262 can be identical versions of the firstjoint disk202.

It has been discovered that the present invention provides themedical instrument100 with simplified manufacturing. Having the firstjoint disk202 and the secondjoint disk232 with the same configuration can simplify the manufacture of thesnake wrist structure110 by reducing the number of unique parts required for assembly. Reducing the number of parts can simplify manufacturing complexity and reduce manufacturing cost.

The firsttoothed gear212 and thesecond tooth slot340 form a rolling joint304 between the firstjoint disk202 and the secondjoint disk232. The rolling joint304 is defined as a structure that forms a multi-axis joint between two elements having multiple degrees of freedom. The rolling joint304 can be the structure where the firstjoint disk202 and the secondjoint disk232 join to creates a rolling motion where the path of the secondjoint disk232 with respect to firstjoint disk202 is defined as the same path as that of the centroid of one circle rolling on the circumference of an identical circle where each circle has a diameter equal to the distance between first slot bearing225 andfirst hole bearing227.

As thesnake wrist structure110 is flexed, the secondjoint disk232 pivots around the firsttoothed gear212 in thesecond tooth slot340. The firsttoothed gear212 coupled with thesecond tooth slot340 provide a constraint with an involute profile on the shape of the firsttoothed gear212 enforcing the rolling motion of the joint. The involute profile of the tooth is defined by the path traced by a point on the circumference of a circle rolling on an identical circle where each circle has a diameter equal to the distance first slot bearing225 andfirst hole bearing227.

Referring now toFIG. 4 therein is shown an exploded side view of thesnake wrist structure110 in a second embodiment. Thesnake wrist structure110 can include thefirst locking member201 and the firstjoint disk202.

Thefirst locking member201 can be connected to the firstinner opening222 of the firstjoint disk202. Thefirst locking member201 is in direct contact with the first slot bearing225 of thefirst strut226 and with a second hole bearing402 of thesecond strut228. Thefirst locking member201 presses against and holds in place the first slot bearing225 and the second hole bearing402.

The firstjoint disk202 is over thefirst locking member201. The secondjoint disk232 is mounted over the firstjoint disk202.

The firstjoint disk202 is connected to the secondjoint disk232 with thefirst strut226. Thefirst strut226 is adjacent to the secondtoothed gear242. Thefirst strut226 can include the first slot bearing225 and the first hole bearing227 connected by thefirst connection link406. The first hole bearing227 is inserted into asecond bearing hole454. The first slot bearing225 is inserted into thefirst tooth slot210.

The secondjoint disk232 is connected to the firstjoint disk202 with thesecond strut228. Thesecond strut228 is adjacent to the firsttoothed gear212. Thesecond strut228 can include a second slot bearing412 and the second hole bearing402 connected by asecond connection link408. The second hole bearing402 is inserted into thefirst bearing hole404. The second slot bearing412 is inserted into thesecond tooth slot340.

Asecond locking element434 is connected to a secondinner opening410 of the secondjoint disk232. Thesecond locking element434 is in direct contact with the first hole bearing227 of thefirst strut226 and the second slot bearing412 of thesecond strut228.

The thirdjoint disk262 is mounted over the secondjoint disk232 with thesecond alignment keys236 interlocked with thethird alignment keys266. Thesecond locking element434 is connected to a thirdinterior portion414 of the thirdjoint disk262.

It has been discovered that the present invention provides themedical instrument100 with improved reliability of operation. The use of the secondtoothed gear242 in thefirst tooth slot210 supports the maintaining of constant length cabling in thesnake wrist structure110. Constant length cabling is defined as a cabling configuration where the cables maintain a constant length. Constant length cabling can insure that as a cable is pulled out of one side of a joint, the opposite side will take up an equal amount of cable.

The firstjoint disk202 and the secondjoint disk232 form a joint that can flex around aflex axis450. Theflex axis450 is defined the effective axis formed by thefirst strut226 and thesecond strut228 when connected between the firstjoint disk202 and the secondjoint disk232.

Referring now toFIG. 5, therein is shown an example of thefirst strut226 in a second embodiment. Thefirst strut226 can include the first slot bearing225, the first hole bearing227, and thefirst connection link406.

Thefirst strut226 can be a two bearing structure for connecting the firstjoint disk202 ofFIG. 2 and the secondjoint disk232 ofFIG. 2. Each bearing can form the axle for a joint disk that allows the joint disk to rotate around the bearing.

The first slot bearing225 can be a structure forming an axle for rotation of the firstjoint disk202. The first slot bearing225 is roughly cylindrical. Thefirst strut226 can include afirst landing surface504 facing thefirst hole bearing227. Thefirst landing surface504 can include a flat surface facing thefirst hole bearing227.

The first slot bearing225 can include afirst locking lip506 on the outer edge of the first slot bearing225 on the side facing away from thefirst hole bearing227. Thefirst locking lip506 can be a structure to prevent motion of the first slot bearing225 by attaching to a matching hole. Thefirst locking lip506 can be at the outer edge of the first hole bearing227 used to engage in a slot or edge to lock the first hole bearing227 in place.

Thefirst strut226 can include a firstslot locking notch508 on the inner edge of the first slot bearing225. The inner edge of the first slot bearing225 is defined as the edge facing thesecond strut228 ofFIG. 2. The first slot bearing225 can include a firstslot bearing surface510 on the side of the first slot bearing225 facing away from thefirst hole bearing227.

Thefirst strut226 can include thefirst connection link406 between the first slot bearing225 and thefirst hole bearing227. Thefirst connection link406 is directly connected to the first slot bearing225 and thefirst hole bearing227.

The first hole bearing227 can be a structure forming an axle for rotation of the secondjoint disk232. The first hole bearing227 is roughly cylindrical. Thefirst strut226 can include the firsthole locking notch514 on the inner edge of thefirst hole bearing227. The inner edge of the first hole bearing227 is the edge facing thesecond strut228. The first hole bearing227 can include a firsthole bearing surface512 on the side of the first hole bearing227 facing away from the first slot bearing225.

Thesnake wrist structure110 can include a variety of strut configuration examples. For example, the strut can include two bearing surfaces on either end of a mechanical link. One bearing surface can connect the strut to a tooth-side bearing on a disk, the other can connect the strut to a slot-side bearing on a disk.

In another example, using two separate but identical struts can create a larger central lumen in the joint than having struts joined together. It has been discovered that the present invention provides a locking feature to prevent the struts from falling out of a joint in the event of a broken or damaged cable.

In yet another example, the bearing surface of the strut can be cantilevered whereby when assembled with a disk, a portion of the bearing surface is aligned underneath the tooth feature. It has been discovered that the this cantilevered geometry allowed for a greater through-lumen size without reducing the bearing surface area of the strut and the corresponding overall load capacity of the joint.

Referring now toFIG. 6 therein is shown an exploded view of thesnake wrist structure110 in a second embodiment. Thesnake wrist structure110 includes thefirst locking member201, the firstjoint disk202, thefirst strut226, thesecond strut228, the secondjoint disk232, thesecond locking element434, and the thirdjoint disk262.

The firstjoint disk202 is over thefirst locking member201. The firstjoint disk202 can include thefirst alignment keys206, the firstangled surface208, thefirst tooth slot210, and the firsttoothed gear212.

Thefirst strut226 can be connected between the firstjoint disk202 and the secondjoint disk232. Thefirst strut226 can include the first hole bearing227, the first slot bearing225, and thefirst connection link406.

Thesecond strut228 can be connected between the firstjoint disk202 and the secondjoint disk232. Thesecond strut228 can include the second hole bearing402, the second slot bearing412, and thesecond connection link408. Thesecond strut228 can have the same configuration as thefirst strut226 rotated 180 degrees in the vertical direction.

The secondjoint disk232 is over the firstjoint disk202. The secondjoint disk232 can include thesecond alignment keys236, the secondangled surface238, the secondtoothed gear242, thesecond bearing hole254, a secondinner opening610, and a set of second cable holes602.

Thesecond locking element434 is between the secondjoint disk232 and the thirdjoint disk262. The thirdjoint disk262 can include thethird alignment keys266, the thirdangled surface268, thethird tooth slot270, the thirdtoothed gear272, and a thirdinner opening612. The thirdjoint disk262 is over thesecond locking element434 and the secondjoint disk232.

The firsttoothed gear212 can include a firsttoothed gear coating604 on the surface of the firsttoothed gear212 to reduce friction between the firstjoint disk202 and the secondjoint disk232. The firsttoothed gear coating604 is defined as a wear resistant material over the surface of the firsttoothed gear212. For example, the firsttoothed gear212 can be manufactured of a variety of medical grade metal alloys. The medical grade metal alloys composition can include Nitronic 60, surgical stainless steel, titanium, nickel, chromium, molybdenum, or a combination thereof. The firsttoothed gear212 can include a wear-resistant coating on the tooth to prevent galling and wear. The firsttoothed gear coating604 can include a variety of medical grade wear-resistant coatings such as diamond-like carbon, thin dense chromium, fluropolymer, or Medcoat 2000. The material of the firsttoothed gear212 and the material of thefirst strut226 can be selected as a complimentary pair for preventing galling.

It has been discovered that the present invention provides themedical instrument100 with improved durability and wear resistance. Including a firsttoothed gear coating604 on the surface of the firsttoothed gear212 can prevent galling and wear on thefirst strut226, leading to an extended operational life of thesnake wrist structure110. The wear-resistant coating can reduce friction between the firstjoint disk202 and the secondjoint disk232 resulting in less wear that can allow the use of softer materials in the manufacture of thefirst strut226.

Thefirst strut226 includes the first slot bearing225 and the first hole bearing227 connected by thefirst connection link406. Thefirst strut226 can support three axes of rotation. The firstjoint disk202 can rotate around the first slot bearing225. The secondjoint disk232 can rotate around thefirst hole bearing227. The first slot bearing225 and the first hole bearing227 can rotate relative to each other and thefirst connection link406.

The first slot bearing225 can include a firstslot bearing surface510 ofFIG. 5. The first hole bearing227 can include a firsthole bearing surface512 ofFIG. 5. Because thefirst strut226 has two bearings, the first slot bearing225 and the first hole bearing227, thefirst strut226 can include a large overall bearing surface area and a higher load capacity. Thus, thefirst strut226 with two bearings can be smaller than a strut with only one bearing for the same load capacity. This allows the overall physical dimensions of thefirst strut226 to be reduced.

It has been discovered that the present invention provides themedical instrument100 with a larger cable payload in thesnake wrist lumen290 because thesnake wrist lumen290 can be larger. Providing thefirst strut226 with two bearings, the first slot bearing225 and the first hole bearing227, reduces the overall size of each bearing by 50% over that needed to support the same load with a single bearing joint. Thefirst strut226 can be of smaller size in terms of bearing diameter, bearing width, or a combination thereof. The smaller version of thefirst strut226 can be used in thesnake wrist structure110 with a thinnerfirst rim209 resulting in an increased diameter of thesnake wrist lumen290. If thesnake wrist lumen290 is larger, the amount of cables and payload in thesnake wrist lumen290 can be increased to provide additional capability for thesnake wrist structure110.

Thefirst strut226 and thesecond strut228 lock the firstjoint disk202 and the secondjoint disk232 together. Locking is defined as holding two elements together in the same relative position and orientation while still allowing the intended rolling motion of the joint. For example, the locking means the firstjoint disk202 and the secondjoint disk232 cannot shift laterally or separate axially, but are still free to pivot. The centroids of the firstjoint disk202 and the secondjoint disk232 maintain the same relative position with respect to each other as one disk pivots with respect to another. Locking can hold the firstjoint disk202 and the secondjoint disk232 in fixed relative positions to one another even in the absence of joint control cables in the first cable holes214 ofFIG. 2 and the second cable holes602.

It has been discovered that the present invention provides themedical instrument100 with improved physical integrity by doubling the mechanisms holding thesnake wrist structure110 together. The physical integrity of thesnake wrist structure110 is increased 100% in terms of preventing accidental disassembly and loss of components during operation. Thefirst strut226 locks the firstjoint disk202 and the secondjoint disk232 together without external connection structures, such as joint control cables or central lumen cables. Locking the firstjoint disk202 and the secondjoint disk232 together can prevent the loss of components of thesnake wrist structure110 in case elements such as the joint control cables are damaged or broken. Preventing the loss of components makes thesnake wrist structure110 safer by reducing the likelihood of a component being lost within a patient during surgery.

Referring now toFIG. 7 therein is shown a cutaway view of thesnake wrist structure110 in a flexed position in a second embodiment. Thesnake wrist structure110 includes thefirst locking member201, the firstjoint disk202, thefirst strut226, the secondjoint disk232, thesecond locking element434, and the thirdjoint disk262.

Thefirst locking member201 is directly connected to the firstinner opening222 of the firstjoint disk202. The firstjoint disk202 is over thefirst locking member201.

The firstjoint disk202 includes the firstangled surface208, thefirst bearing hole404 and the firstinner opening222. Thefirst strut226 is mounted between the firstjoint disk202 and the secondjoint disk232. The first slot bearing225 of thefirst strut226 is mounted in thefirst bearing hole404.

Thefirst strut226 is held in place by thefirst locking member201. Thefirst locking member201 is in direct contact with the firstslot locking notch508 of the first slot bearing225. The first slot bearing225 prevents thefirst strut226 from slipping into the firstinner opening222 of the firstjoint disk202.

The secondjoint disk232 includes the secondangled surface238, the secondtoothed gear242, and the secondinner opening410 ofFIG. 4. The first hole bearing227 of thefirst strut226 is inserted in thesecond bearing hole254. The firstangled surface208 can include a portion that is part of thefirst cable cutout216. The secondangled surface238 includes a secondangled surface cutout708.

The secondjoint disk232 is shown in a flexed position with the one side of the secondangled surface238 in direct contact with the firstangled surface208 of the firstjoint disk202. The secondjoint disk232 can rotate around the first hole bearing227 of thefirst strut226. The firstjoint disk202 can rotate around the first slot bearing225 of thefirst strut226.

The maximum degree of deflection between the firstjoint disk202 and the secondjoint disk232 is limited by the geometry of the firstangled surface208 and the secondangled surface238. For example, the firstangled surface208 and the secondangled surface238 are each at an angle of 22.5 degrees from the horizontal. The maximum deflection between the firstjoint disk202 and the secondjoint disk232 is 45 degrees.

It has been discovered that the present invention provides themedical instrument100 with simplified manufacturing. The firstangled surface208 and the secondangled surface238 can be used to limit the degree of flex in thesnake wrist structure110 without further device or limiting mechanisms. The meeting of the firstangled surface208 and the secondangled surface238 limits the degree of flex and thus eliminates the need for external limiters, such as gear mechanisms or strut, and internal limitation features such as bumps, spacers, stoppers, tabs, or a combination thereof, and simplify manufacturing complexity and reduce manufacturing costs.

The secondtoothed gear242 of the secondjoint disk232 remains partially in thefirst tooth slot210 of the firstjoint disk202 as thesnake wrist structure110 is flexed. In the flexed position, the tip of the secondtoothed gear242 is within thefirst tooth slot210. As the secondjoint disk232 is unflexed, the shape of the secondtoothed gear242 allows the secondtoothed gear242 to slide back into thefirst tooth slot210 as the secondjoint disk232 returns to a non-flexed position. The secondtoothed gear242 and thefirst tooth slot210 act together to align the firstjoint disk202 and the secondjoint disk232 during flexing of thesnake wrist structure110.

It has been discovered that the present invention provides themedical instrument100 with improved reliability of operation. The position and shape of the secondtoothed gear242 in thefirst tooth slot210 can align the firstjoint disk202 and the secondjoint disk232 during the flexing of thesnake wrist structure110. When thesnake wrist structure110 is flexed or unflexed, the tip of the secondtoothed gear242 is in thefirst tooth slot210 and guides the secondtoothed gear242 smoothly into thefirst tooth slot210, preventing misalignment and dislocation of the secondtoothed gear242.

Thesecond locking element434 is directly connected to the second inner opening of the secondjoint disk232. Thesecond locking element434 is over thesecond locking element434. Thesecond locking element434 is directly connected to the thirdinterior portion414 of the thirdjoint disk262.

The thirdjoint disk262 is over the secondjoint disk232. The thirdjoint disk262 is directly connected the secondjoint disk232 with thesecond alignment keys236 of the secondjoint disk232 interlocking with thethird alignment keys266 of the thirdjoint disk262. The thirdjoint disk262 includes the thirdtoothed gear272 and the thirdinner opening612.

Referring now toFIG. 8 therein is shown an isometric view of thesnake wrist structure110 in an unflexed position in a second embodiment. Thesnake wrist structure110 can include the firstjoint disk202, thefirst strut226, thesecond strut228, the secondjoint disk232, and thesnake wrist lumen290.

The firstjoint disk202 can include thefirst alignment keys206, the firstangled surface208, the first cable holes214 ofFIG. 2, thefirst cable cutouts216 ofFIG. 2, the firsttoothed gear212, and thefirst tooth slot210. The firstjoint disk202 is below the secondjoint disk232.

The first cable holes214 are defined as opening for passing joint control cables through joint disks. The first cable holes214 can be openings extending through the firstjoint disk202 to provide access for the joint control cables (not shown). The joint control cables are defined as cables that are used to control the flexing of joints in thesnake wrist structure110.

The first cable holes214 are adjacent to the firstangled surface208. The firstjoint disk202 can include thefirst cable cutouts216 around the first cable holes214 on the same side of the firstjoint disk202 as the firstangled surface208. Thefirst cable cutouts216 can be beveled areas around the first cable holes214 to accommodate motion of the joint control cables when thesnake wrist structure110 is flexed. Thefirst cable cutouts216 are around the first cable holes214 and can include a portion of the firstangled surface208. Thefirst cable cutouts216 are beveled to reduce abrasion of the joint control cables against the sides of the first cable holes214 when thesnake wrist structure110 is flexed.

The secondjoint disk232 can include the secondtoothed gear242, thesecond bearing hole254, thesecond alignment keys236, the second cable holes602, the secondangled surface238, and the secondinner opening410. The secondjoint disk232 is over the firstjoint disk202.

The second cable holes602 provide access for the joint control cables through the secondjoint disk232. The joint control cables can extend the length of thesnake wrist structure110 and run through the cables holes of each joint disk. The second cable holes602 are aligned with the first cable holes214 to allow the joint control cables to pass through both the firstjoint disk202 and the secondjoint disk232.

The firstjoint disk202 and the secondjoint disk232 are connected with thefirst strut226 and thesecond strut228. Thesecond strut228 is in thesecond bearing hole254. The secondtoothed gear242 is in thefirst tooth slot210.

Referring now toFIG. 9 therein is shown a front view of thesnake wrist structure110 in a second embodiment. Thesnake wrist structure110 can include the firstjoint disk202, the secondjoint disk232, thefirst strut226, and thesecond strut228.

The firstjoint disk202 can include thefirst alignment keys206, the firstangled surface208 and the firsttoothed gear212. The firstjoint disk202 and the secondjoint disk232 are connected with thefirst strut226 and thesecond strut228.

Thefirst strut226 is adjacent to the secondtoothed gear242. Thesecond strut228 is adjacent to the firsttoothed gear212.

The secondjoint disk232 can include the secondtoothed gear242, the secondangled surface238, and thesecond alignment keys236. The secondjoint disk232 is over the firstjoint disk202.

Referring now toFIG. 10 therein is shown an isometric view of the firstjoint disk202. The firstjoint disk202 can be in a variety of different embodiments. The firstjoint disk202 can include thefirst alignment keys206, the firstangled surface208, the firsttoothed gear212, thefirst tooth slot210, thefirst rim209, the firstinner opening222, the first cable holes214, and thefirst cable cutouts216.

The firstjoint disk202 can include the firsttoothed gear212 on thefirst rim209. Thefirst bearing hole404 is directly below the firsttoothed gear212 between the firsttoothed gear212 and one of thefirst alignment keys206 on the bottom side of the firstjoint disk202.

The firstjoint disk202 can include thefirst tooth slot210 on thefirst rim209 opposite from the firsttoothed gear212. The firstjoint disk202 can include the first cable holes214 and thefirst cable cutouts216 along thefirst rim209 between the firsttoothed gear212 and thefirst tooth slot210. The firstinner opening222 is between the firsttoothed gear212 and thefirst tooth slot210.

Referring now toFIG. 11 therein is shown a top view of the firstjoint disk202 in a second embodiment. The firstjoint disk202 can include the first cable holes214, thefirst cable cutouts216, the firsttoothed gear212, a firstbearing mounting hole1108, afirst bearing slot1106, and thefirst tooth slot210.

The firstjoint disk202 can include afirst bearing bed1102 and asecond bearing bed1104. Thefirst bearing bed1102 can be a surface where a bearing can be placed. Thefirst bearing bed1102 can be a space between the firstbearing mounting hole1108 and thefirst tooth slot210. Thesecond bearing bed1104 can be a surface where a bearing can be placed. Thesecond bearing bed1104 can be a space between thefirst bearing slot1106 and thefirst bearing hole404.

The firstbearing mounting hole1108 is defined as a structural element for supporting the inner side of the second hole bearing402 ofFIG. 4. The firstbearing mounting hole1108 can be an hole in the firstinner ring1110. The firstbearing mounting hole1108 is adjacent to thefirst tooth slot210.

The firstjoint disk202 can include afirst bearing slot1106. Thefirst bearing slot1106 is defined as a structure that can support one side of a cylindrical bearing. Thefirst bearing slot1106 can be an opening in thefirst rim209 ofFIG. 2 of the firstjoint disk202 opposite the firsttoothed gear212 for accommodating thefirst locking lip506 ofFIG. 5 of thefirst strut226 ofFIG. 2.

The firstjoint disk202 can include the first cable holes214 for accommodating the joint control cables. Each joint control cable can pass through two of the first cable holes214 on opposite sides of theflex axis450 ofFIG. 4. The first cable holes214 can form in pairs of holes that are each equally spaced away from theflex axis450 and on a line perpendicular to theflex axis450 that passes through the center of the pair of holes.

Referring now toFIG. 12 therein is shown an isometric view of the bottom of the firstjoint disk202 in a second embodiment. The firstjoint disk202 can include thefirst tooth slot210, the firstangled surface208, the first cable holes214, thefirst alignment keys206, and the firstinner opening222.

The firstjoint disk202 can include an interlocking structure on the bottom of the firstjoint disk202 for connecting the firstjoint disk202 to another element or other mounting structure. The interlocking structure can hold the firstjoint disk202 and another disk element in a fixed orientation. The interlocking structure can include a variety of mating structures including thefirst alignment keys206 with the firstalignment key tab203 ofFIG. 2 and the first alignmentkey hole205 ofFIG. 2, a rib and slot structure, a pin and hole structure, a grooved structure, or a combination thereof.

For example, thefirst alignment keys206 can be four interlocking structures positioned at 90 degree intervals around the bottom of the firstjoint disk202. One of thefirst alignment keys206 is under thefirst tooth slot210. One of thefirst alignment keys206 is opposite thefirst tooth slot210 and under the firsttoothed gear212. The other twofirst alignment keys206 are under the lowest points of the firstangled surface208.

The firstjoint disk202 can include the first cable holes214 arranged around the firstinner opening222. The first cable holes214 are arranged between thefirst alignment keys206 and evenly distributed between each adjacent pair of thefirst alignment keys206. The first cable holes214 can have a beveled edge on the bottom of the firstjoint disk202 to reduce cable abrasion.

The firstjoint disk202 can include the firstinner opening222. The firstinner opening222 is an opening in thecentral portion302 of the firstjoint disk202. The firstinner opening222 can form a portion of thesnake wrist lumen290 ofFIG. 2.

Thesnake wrist structure110 can include a variety of joint disk configuration examples. For example, the joint disk can include two angled surfaces set at 22.5 degrees to the horizontal plane that set the range of motion limit stops for the assembled joint at ±45 degrees. The joint disk can include a plurality of through-holes around the perimeter (but not present in the center plane that lies parallel to the pivot axis or the center plane perpendicular to that plane) that allow actuation cables to pass through the joint. This can include 12 holes around the perimeter but this could also be any even number of holes (2, 4, 8, 12, 16, etc. . . . ). The joint disk can include an involute “tooth” feature on one side and a corresponding “tooth-notch” on the opposite side. The joint disk can include two cylindrical concave bearing surfaces, one next-to and underneath the “tooth” feature and one next-to and underneath the “tooth-notch” feature. The joint disk can include a set of mating post and slot features on the bottom face that allow each disk to mate with the bottom face of an adjacent disk in such away that the cylindrical portions of the two disks are concentric and have a fixed orientation with respect to each other about the central axis of the disks. Also, these mating features allow the disks to be mated in fixed 90 degree increments with respect to one another. The joint disk can include surfaces and features that, when paired with mating parts, act to lock the “joint assembly” subcomponents to one another whereby they cannot be removed except by un-stacking the chain of multiple “joint assemblies” that form the instrument snake wrist.

Referring now toFIG. 13A therein is shown a first isometric view of thesnake wrist structure110 in a third embodiment. Thesnake wrist structure110 can include afirst locking member1301, a firstjoint disk1302, a secondjoint disk1332, a thirdjoint disk1362, and asnake wrist lumen1390.

Thesnake wrist structure110 has a firsttransverse dimension1396 and a secondtransverse dimension1398 along a plane orthogonal to thecentral axis119 ofFIG. 1. The firsttransverse dimension1396 and the secondtransverse dimension1398 are shown to be the same but do not need to be and may be adjusted based on the geometry of thesnake wrist structure110. In the case in which they are equal, thesnake wrist structure110 may be circular in cross section as illustrated inFIG. 2. As an example, the firsttransverse dimension1396 and the secondtransverse dimension1398 are shown to be along directions perpendicular to each other but does not necessarily required to be perpendicular.

Thesnake wrist structure110 includes thefirst locking member1301 connected to the firstjoint disk1302. Thefirst locking member1301 can be a cylindrical tube with an outer diameter approximately equal to a diameter of a firstinner opening1322 of the firstjoint disk1302. Thefirst locking member1301 forms a tight fit with the firstinner opening1322 when connected to the firstjoint disk1302.

The firstjoint disk1302 can include the firstinner opening1322. The firstinner opening1322 is defined as the central unobstructed through lumen of the firstjoint disk1302. A lumen is defined as an internal cavity or opening in a cylindrical structure. The firstinner opening1322 is an opening in acentral portion1375 of the firstjoint disk1302. The firstinner opening1322 can form a portion of thesnake wrist lumen1390. Thecentral portion1375 is defined as the interior part of the firstjoint disk1302 surrounding thecentral axis119 ofFIG. 1.

The firstjoint disk1302 can be a structural element that can be coupled to other similar disks to form thesnake wrist structure110 having the firstinner opening1322 in the center of the firstjoint disk1302. The inner openings of the coupled disks of thesnake wrist structure110 form thesnake wrist lumen1390 ofFIG. 13A in thesnake wrist structure110.

Thesnake wrist lumen1390 is defined as a channel in thesnake wrist structure110 that can be used to pass mechanical, electrical, or optical cables or other control tubes. Thesnake wrist lumen1390 can also be a through lumen for providing fluid or gas delivery or extraction, or for use as a through lumen in the instrument to allow for the passage of secondary smaller diameter surgical tools through the snake joint assembly such as a biopsy needle, grasper, or laser fiber.

The firstjoint disk1302 can include a set offirst alignment ribs1303 and a set offirst alignment slots1305 around the outer diameter of the firstjoint disk1302 for attaching with other joint disks. Thefirst alignment ribs1303 are defined as structures for connected the firstjoint disk1302 to another element and for preventing rotation of the firstjoint disk1302 relative to the other element. Thefirst alignment ribs1303 can be a portion of the outer diameter of the firstjoint disk1302. Thefirst alignment slots1305 are defined as structures for connecting to and accommodating thefirst alignment ribs1303. Thefirst alignment slots1305 can be the portions of the outer diameter of the firstjoint disk1302 that are not thefirst alignment ribs1303. Thefirst alignment ribs1303 and thefirst alignment slots1305 are equal in size as measured around the outer diameter of the firstjoint disk1302.

For example, the firstjoint disk1302 can have two of thefirst alignment ribs1303 and two of thefirst alignment slots1305 around the outer diameter of the firstjoint disk1302. Thefirst alignment ribs1303 and thefirst alignment slots1305 can each be 25% of the outer diameter of the firstjoint disk1302.

In a further example, thefirst alignment ribs1303 are distributed 180 degrees apart from one another around the outer diameter of the firstjoint disk1302. Thefirst alignment ribs1303 can be inserted in the alignment slots of another disk. Thefirst alignment slots1305 are distributed 180 degrees apart from on another around the outer diameter of the firstjoint disk1302 and 90 degrees apart from thefirst alignment ribs1303.

The firstjoint disk1302 can include a firsttoothed gear1312 on afirst rim1371 of the firstjoint disk1302. The firsttoothed gear1312 can be a single toothed gear extending from thefirst rim1371 of the firstjoint disk1302. The firsttoothed gear1312 is centered over afirst bearing hole1354. A second hole bearing1337 can be in thefirst bearing hole1354.

The firstjoint disk1302 can include a firstangled surface1308 around both sides thefirst rim1371 of the firstjoint disk1302 between the firsttoothed gear1312 to the point on thefirst rim1371 opposite the firsttoothed gear1312. The firstangled surface1308 extends in downward directions from the base of the firsttoothed gear1312 and the point on thefirst rim1371 opposite the firsttoothed gear1312 and reaches a maximum depth midway between the firsttoothed gear1312 and the opposite point. The firstangled surface1308 is formed at an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

Thefirst rim1371 is defined as a structural element around the circumference of the top of the firstjoint disk1302. Thefirst rim1371 can include the firsttoothed gear1312 and the firstangled surface1308.

Thesnake wrist structure110 can include the secondjoint disk1332. The secondjoint disk1332 can have the same configuration as the firstjoint disk1302. The secondjoint disk1332 is mounted over the firstjoint disk1302 in an inverted position and rotated 180 degrees.

The secondjoint disk1332 can include asecond tooth slot1340, a secondangled surface1338, a set ofsecond alignment ribs1333, and a set ofsecond alignment slots1335. The firsttoothed gear1312 is inserted in thesecond tooth slot1340. A second slot bearing1339 can be in thesecond tooth slot1340.

The secondangled surface1338 is over the firstangled surface1308. The secondangled surface1338 faces the firstangled surface1308.

The secondjoint disk1332 can include thesecond alignment ribs1333 and thesecond alignment slots1335 around the outer diameter of the secondjoint disk1332 for attaching with other joint disks. Thesecond alignment ribs1333 are defined as structures for connecting the secondjoint disk1332 with another joint disk in a fixed orientation and to prevent rotation of the secondjoint disk1332 relative to the other joint disk. Thesecond alignment slots1335 are defined as the portions of the outer diameter of the secondjoint disk1332 that are not thesecond alignment ribs1333. Thesecond alignment ribs1333 and thesecond alignment slots1335 are equal in size as measured around the outer diameter of the secondjoint disk1332.

For example, the secondjoint disk1332 can have two of thesecond alignment ribs1333 and two of thesecond alignment slots1335 around the outer diameter of the secondjoint disk1332. Thesecond alignment ribs1333 and thesecond alignment slots1335 can each be 25% of the outer diameter of the secondjoint disk1332.

In a further example, thesecond alignment ribs1333 are distributed 180 degrees apart from one another around the outer diameter of the secondjoint disk1332. Thesecond alignment ribs1333 can be inserted in the alignment slots of another disk. Thesecond alignment slots1335 are distributed 180 degrees apart from on another around the outer diameter of the secondjoint disk1332 and 90 degrees apart from thesecond alignment ribs1333.

The secondjoint disk1332 can include the secondangled surface1338 around both sides of asecond rim1373 of the secondjoint disk1332. The secondangled surface1338 extends in a semicircular arc in an downward direction from thesecond tooth slot1340 reaching a maximum depth midway between thesecond tooth slot1340 and the point opposite thesecond tooth slot1340 on thesecond rim1373 of the secondjoint disk1332. The secondangled surface1338 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

It has been discovered that the present invention provides themedical instrument100 with simplified manufacturing. The firstangled surface1308 and the secondangled surface1338 can be used to limit the degree of flex in thesnake wrist structure110 without further device or limiting mechanisms. The meeting of the firstangled surface1308 and the secondangled surface1338 limits the degree of flex and thus eliminates the need for external limiters, such as gear mechanisms or strut, and internal limitation features such as bumps, spacers, stoppers, tabs, or a combination thereof, and simplify manufacturing complexity and reduce manufacturing costs.

Thesnake wrist structure110 can include the thirdjoint disk1362. The thirdjoint disk1362 can have the same configuration as the firstjoint disk1302 and the secondjoint disk1332. The thirdjoint disk1362 is mounted over and directly in contact with the secondjoint disk1332.

The thirdjoint disk1362 can include a set ofthird alignment ribs1363 and a set ofthird alignment slots1365 around the outer diameter of the thirdjoint disk1362 for attaching with other joint disks. Thethird alignment ribs1363 are defined as structures for connecting the thirdjoint disk1362 with another joint disk in a fixed orientation and to prevent rotation of the thirdjoint disk1362 relative to the other joint disk. Thethird alignment slots1365 are defined as the portions of the outer diameter of the thirdjoint disk1362 that are not thethird alignment ribs1363. Thethird alignment ribs1363 and thethird alignment slots1365 are equal in size as measured around the outer diameter of the thirdjoint disk1362.

For example, the thirdjoint disk1362 can have two of thethird alignment ribs1363 and two of thethird alignment slots1365 around the outer diameter of the thirdjoint disk1362. Thethird alignment ribs1363 and thethird alignment slots1365 can each be 25% of the outer diameter of the thirdjoint disk1362.

In a further example, thethird alignment ribs1363 are distributed 180 degrees apart from one another around the outer diameter of the thirdjoint disk1362. Thethird alignment ribs1363 can be inserted in the alignment slots of another disk. Thethird alignment slots1365 are distributed 180 degrees apart from on another around the outer diameter of the thirdjoint disk1362 and 90 degrees apart from thethird alignment ribs1363.

The thirdjoint disk1362 can include athird tooth slot1370 and a thirdtoothed gear1372. The thirdjoint disk1362 can be mounted over the secondjoint disk1332 whereby thethird tooth slot1370 and the thirdtoothed gear1372 are rotated 90 degrees away from thesecond tooth slot1340. Thethird tooth slot1370 and the thirdtoothed gear1372 are on the opposite side of the thirdjoint disk1362 from the secondjoint disk1332.

The firsttoothed gear1312 can include a firsttoothed gear coating1383 on the surface of the firsttoothed gear1312 to reduce friction between the firstjoint disk1302 and the secondjoint disk1332. The first toothed gear coating1382 is defined as a wear resistant material over the surface of the firsttoothed gear1312. For example, the firsttoothed gear1312 can be manufactured of a variety of medical grade metal alloys. The medical grade metal alloys composition can include Nitronic 60, surgical stainless steel, titanium, nickel, chromium, molybdenum, or a combination thereof. The firsttoothed gear1312 can include a wear-resistant coating on the tooth to prevent galling and wear. The firsttoothed gear coating1383 can include a variety of medical grade wear-resistant coatings such as diamond-like carbon, thin dense chromium, fluropolymer, or Medcoat 2000.

It has been discovered that the present invention provides themedical instrument100 with improved durability and wear resistance. Including a firsttoothed gear coating1383 on the surface of the firsttoothed gear1312 can prevent galling and wear on thefirst strut1526, leading to an extended operational life of thesnake wrist structure110. The wear-resistant coating can reduce friction between the firstjoint disk1302 and the secondjoint disk1332 resulting in less wear that can allow the use of softer materials in the manufacture of thefirst strut1526.

Thesnake wrist structure110 can flex in a variety of ways with different degrees of freedom. For example, when the secondjoint disk1332 is flexed toward one side of thesnake wrist structure110, the angular degree of flex is limited by the geometry of the firstangled surface1308 and the secondangled surface1338. The secondjoint disk1332 can only flex a maximum of 45 degrees if when the firstangled surface1308 and the secondangled surface1338 each form a 22.5 degree angle from the horizontal plane. The range of motion of the secondjoint disk1332 is limited by when the firstangled surface1308 and the secondangled surface1338 meet and prevent further motion.

The firstjoint disk1302, the secondjoint disk1332, and the thirdjoint disk1362 can all have the same configuration. For example, the secondjoint disk1332 and the thirdjoint disk1362 can be identical versions of the firstjoint disk1302.

It has been discovered that having the firstjoint disk1302 and the secondjoint disk1332 with the same configuration can simplify the manufacture of thesnake wrist structure110 by reducing the number of unique parts required for assembly. Reducing the number of parts can simplify manufacturing complexity and reduce manufacturing cost.

Thesnake wrist structure110 can include ajoint knuckle1395. Thejoint knuckle1395 is formed by connecting the firstjoint disk1302 to the second joint disk. Thejoint knuckle1395 can have an interconnect structure on the proximal and distal ends to facilitate connecting to a further member such as a joint knuckle, instrument, mounting member, or a combination thereof.

Referring now toFIG. 13B therein is shown a second isometric view of thesnake wrist structure110 in a third embodiment. Thesnake wrist structure110 can include the firstjoint disk1302, the secondjoint disk1332, and aflex axis1350.

The firstjoint disk1302 and the secondjoint disk1332 form a joint that can flex around theflex axis1350. Theflex axis1350 is defined as the effective axis between the firstjoint disk1302 and the secondjoint disk1332.

The firsttoothed gear1312 and thesecond tooth slot1340 form a rolling joint1352 between the firstjoint disk1302 and the secondjoint disk1332. The rolling joint1352 is defined as a structure that forms a multi-axis joint between two elements having multiple degrees of freedom. The rolling joint1352 can be the structure where the firstjoint disk1302 and the secondjoint disk1332 join to creates a rolling motion whereby the path of the secondjoint disk1332 with respect to firstjoint disk1302 is defined as the same path as that of the centroid of one circle rolling on the circumference of an identical circle where each circle has a diameter equal to the distance between the second slot bearing1339 and thesecond hole bearing1337.

As thesnake wrist structure110 is flexed, the secondjoint disk1332 pivots around the firsttoothed gear1312 in thesecond tooth slot1340. The firsttoothed gear1312 coupled with thesecond tooth slot1340 provide a constraint with an involute profile on the shape of the firsttoothed gear1312 enforcing the rolling motion of the joint. The involute profile of the tooth is defined by the path traced by a point on the circumference of a circle rolling on an identical circle where each circle has a diameter equal to the distance between the second slot bearing1339 and thesecond hole bearing1337.

Referring now toFIG. 14 therein is shown a side view of thesnake wrist structure110 in an unflexed position in a third embodiment. Thesnake wrist structure110 can include thefirst locking member1301, the firstjoint disk1302, the secondjoint disk1332, and the thirdjoint disk1362.

Thefirst locking member1301 is connected to the firstjoint disk1302. The firstjoint disk1302 is over thefirst locking member1301.

The firstjoint disk1302 can include thefirst alignment ribs1303, thefirst alignment slots1305, the firstangled surface1308, and the firsttoothed gear1312.

The secondjoint disk1332 can include the secondangled surface1338, thesecond tooth slot1340, thesecond alignment ribs1333, and thesecond alignment slots1335. The secondjoint disk1332 is over the firstjoint disk1302.

The thirdjoint disk1362 can include thethird alignment ribs1363, thethird alignment slots1365, the thirdtoothed gear1372, and a thirdangled surface1385. The thirdjoint disk1362 is over the secondjoint disk1332.

The thirdjoint disk1362 is rotated whereby thethird alignment ribs1363 are directly over thesecond alignment slots1335. The thirdjoint disk1362 is directly connected to the secondjoint disk1332. Thethird alignment ribs1363 are in direct contact with thesecond alignment slots1335 to connect the secondjoint disk1332 and the thirdjoint disk1362.

For example, the thirdjoint disk1362 can be rotated 90 degrees around thecentral axis119 ofFIG. 13A and mounted on the secondjoint disk1332. By mounting the thirdjoint disk1362 at a 90 degree angle to the secondjoint disk1332, thesnake wrist structure110 can flex orthogonally to theflex axis1350 ofFIG. 13A of the firstjoint disk1302 and the secondjoint disk1332.

In another example, the thirdjoint disk1362 can be rotated 180 degrees around thecentral axis119 and mounted on the secondjoint disk1332. By mounting the thirdjoint disk1362 at a 180 degree angle to the secondjoint disk1332, thesnake wrist structure110 can flex further around theflex axis1350.

Referring now toFIG. 15 therein is shown an exploded view of thesnake wrist structure110 in a third embodiment. Thesnake wrist structure110 includes thefirst locking member1301, the firstjoint disk1302, the secondjoint disk1332, afirst strut1526, asecond strut1528, asecond locking element1534, and the thirdjoint disk1362.

The firstjoint disk1302 is over thefirst locking member1301. The firstjoint disk1302 can include thefirst alignment ribs1303, thefirst alignment slots1305, the firstangled surface1308, afirst tooth slot1510, the firsttoothed gear1312 and the first cable holes1502.

The firstjoint disk1302 can include afirst tooth slot1510 on thefirst rim1371 of the firstjoint disk1302. Thefirst tooth slot1510 can be a concave opening in thefirst rim1371 of the firstjoint disk1302.

The secondjoint disk1332 is over the firstjoint disk1302. The secondjoint disk1332 can include thesecond alignment ribs1333, thesecond alignment slots1335, the secondangled surface1338, thesecond tooth slot1340, a secondtoothed gear1542, and a set of second cable holes1532.

Thefirst strut1526 can be connected between the firstjoint disk1302 and the secondjoint disk1332. Thefirst strut1526 can include thefirst hole bearing1527, thefirst slot bearing1525, and thefirst connection link1506.

Thesecond strut1528 can be connected between the firstjoint disk1302 and the secondjoint disk1332. Thesecond strut1528 can include the second hole bearing1337, the second slot bearing1339, and asecond connection link1508. Thesecond strut1528 can have the same configuration as thefirst strut1526 rotated 180 degrees in the vertical direction.

Thesecond locking element1534 is between the secondjoint disk1332 and the thirdjoint disk1362. The thirdjoint disk1362 is over thesecond locking element1534 and the secondjoint disk1332. The thirdjoint disk1362 can include thethird alignment ribs1363, thethird alignment slots1365, the thirdangled surface1385, thethird tooth slot1370, and the thirdtoothed gear1372.

Thefirst strut1526 includes thefirst slot bearing1525 and thefirst hole bearing1527 connected by thefirst connection link1506. Thefirst strut1526 can support three axes of rotation. The firstjoint disk1302 can rotate around thefirst slot bearing1525. The secondjoint disk1332 can rotate around thefirst hole bearing1527. Thefirst slot bearing1525 and thefirst hole bearing1527 can rotate relative to each other and thefirst connection link1506.

The first slot bearing1525 can include a firstslot bearing surface1509. Thefirst hole bearing1527 can include a firsthole bearing surface1512. Because thefirst strut1526 has two bearings, thefirst slot bearing1525 and thefirst hole bearing1527, thefirst strut1526 can include a large overall bearing surface area and a higher load capacity. Thus, thefirst strut1526 with two bearings can be smaller than a strut with only one bearing for the same load capacity. This allows the overall physical dimensions of thefirst strut1526 to be reduced.

It has been discovered that the present invention provides themedical instrument100 with a larger cable payload in thesnake wrist lumen1390 because thesnake wrist lumen1390 can be larger. Providing thefirst strut1526 with two bearings, thefirst slot bearing1525 and thefirst hole bearing1527, reduces the overall size of each bearing by 50% over that needed to support the same load with a single bearing joint. Thefirst strut1526 can be of smaller size in terms of bearing diameter, bearing width, or a combination thereof. The smaller version of thefirst strut1526 can be used in thesnake wrist structure110 with a thinnerfirst rim1371 resulting in an increased diameter of thesnake wrist lumen1390. If thesnake wrist lumen1390 is larger, the amount of cables and payload in thesnake wrist lumen1390 can be increased to provide additional capability for thesnake wrist structure110.

Thefirst strut1526 and thesecond strut1528 can lock the firstjoint disk1302 and the secondjoint disk1332 together. Locking is defined as holding two elements together in the same relative position and orientation while still allowing the intended rolling motion of the joint. For example, the locking means the firstjoint disk1302 and the secondjoint disk1332 cannot shift laterally or separate axially, but are still free to pivot. The centroids of the firstjoint disk1302 and the secondjoint disk1332 maintain the same relative position with respect to each other as one disk pivots with respect to another. Locking can hold the firstjoint disk1302 and the secondjoint disk1332 in fixed relative positions to one another even in the absence or failure of joint control cables.

It has been discovered that the present invention provides themedical instrument100 with improved physical integrity by doubling the mechanisms holding thesnake wrist structure110 together. The physical integrity of thesnake wrist structure110 is increased 100% in terms of preventing accidental disassembly and loss of components during operation. Thefirst strut1526 locks the firstjoint disk1302 and the secondjoint disk1332 together without external connection structures, such as joint control cables or central lumen cables. Locking the firstjoint disk1302 and the secondjoint disk1332 together can prevent the loss of components of thesnake wrist structure110 in case elements such as the joint control cables are damaged or broken. Preventing the loss of components makes thesnake wrist structure110 safer by reducing the likelihood of a component being lost within a patient during surgery.

It has also been discovered that the present invention provides themedical instrument100 with improved reliability of operation. The use of the secondtoothed gear1542 in thefirst tooth slot1510 supports the maintaining of constant length cabling in thesnake wrist structure110. Constant length cabling can be achieved by insuring that as a cable is pulled out of one side of a joint, the side opposite cable will take up an equal length of cable.

The secondtoothed gear1542 of the secondjoint disk1332 remains partially in thefirst tooth slot1510 of the firstjoint disk1302 as thesnake wrist structure110 is flexed. In the flexed position, the tip of the secondtoothed gear1542 is within thefirst tooth slot1510. As the secondjoint disk1332 is unflexed, the shape of the secondtoothed gear1542 allows the secondtoothed gear1542 to slide back into thefirst tooth slot1510 as the secondjoint disk1332 returns to a non-flexed position. The secondtoothed gear1542 and thefirst tooth slot1510 act together to align the firstjoint disk1302 and the secondjoint disk1332 during flexing of thesnake wrist structure110.

It has been discovered that the present invention provides themedical instrument100 with improved reliability of operation. The position and shape of the secondtoothed gear1542 in thefirst tooth slot1510 can align the firstjoint disk1302 and the secondjoint disk1332 during the flexing of thesnake wrist structure110. When thesnake wrist structure110 is flexed or unflexed, the tip of the secondtoothed gear1542 is in thefirst tooth slot1510 and guides the secondtoothed gear1542 smoothly into thefirst tooth slot1510, preventing misalignment and dislocation of the secondtoothed gear1542.

Referring now toFIG. 16 therein is shown an isometric view of the firstjoint disk1302 in a third embodiment. The firstjoint disk1302 can include thefirst alignment ribs1303, thefirst alignment slots1305, the firstangled surface1308, the firsttoothed gear1312, thefirst tooth slot1510, the firstinner opening1322, thefirst cable holes1502, and thefirst cable cutouts1616. The firstjoint disk1302 can include afirst rim1371, the firstinner ring1604, thefirst bearing hole1354, thefirst bearing slot1615, the firstbearing mounting hole1617.

For example, thefirst alignment ribs1303 and thefirst alignment slots1305 are on the circumference of the bottom side of the firstjoint disk1302. Thefirst alignment ribs1303 can each extend 25% of the circumference of the firstjoint disk1302. Thefirst alignment slots1305 can each extend 25% of the circumference of the firstjoint disk1302. A portion of thefirst bearing hole1354 can extend into thefirst alignment slots1305.

The firstjoint disk1302 can include the firsttoothed gear1312 on thefirst rim1371. Thefirst bearing hole1354 is directly below the firsttoothed gear1312.

The firstjoint disk1302 can include thefirst tooth slot1510 on thefirst rim1371 opposite from the firsttoothed gear1312. The firstjoint disk1302 can include the firstbearing mounting hole1617 on the firstinner ring1604 on the same side as thefirst tooth slot1510.

The firstjoint disk1302 can include thefirst cable holes1502 and thefirst cable cutouts1616 between thefirst rim1371 and the firstinner ring1604. The firstinner ring1604 is around the firstinner opening1322. The firstinner opening1322 is between thefirst bearing slot1615 and the firstbearing mounting hole1617.

The firstjoint disk1302 can include the firstinner opening1322. The firstinner opening1322 is an opening in acentral portion1603 of the firstjoint disk1302.

Referring now toFIG. 17 therein is shown a side view of the firstjoint disk1302 in a third embodiment. The firstjoint disk1302 can include thefirst alignment ribs1303, thefirst alignment slots1305, the firstangled surface1308, the firsttoothed gear1312, and thefirst bearing hole1354.

For example, thefirst alignment ribs1303 and thefirst alignment slots1305 are on the circumference of the bottom side of the firstjoint disk1302. Thefirst alignment ribs1303 can each extend 25% of the circumference of the firstjoint disk1302. Thefirst alignment slots1305 can each extend 25% of the circumference of the firstjoint disk1302. A portion of thefirst bearing hole1354 can extend into thefirst alignment slots1305.

The firstjoint disk1302 can include the firsttoothed gear1312 on thefirst rim1371. Thefirst bearing hole1354 is directly below the firsttoothed gear1312 between the firsttoothed gear1312 and one of thefirst alignment slots1305 on the bottom side of the firstjoint disk1302.

Referring now toFIG. 18 therein is shown an isometric view of the bottom of the firstjoint disk1302 in a third embodiment. The firstjoint disk1302 can include thefirst cable holes1502, thefirst alignment ribs1303, thefirst alignment slots1305, and the firstinner opening1322.

The firstjoint disk1302 can include an interlocking structure for connecting the firstjoint disk1302 to another disk element or other mounting structure. The interlocking structure can hold the firstjoint disk1302 and another disk element in a fixed orientation. The interlocking structure can include a variety of mating structures including thefirst alignment ribs1303 and thefirst alignment slots1305, an alignment hole, a tab and hole structure, a pin and hole structure, a grooved structure, or a combination thereof.

For example, thefirst alignment ribs1303 and thefirst alignment slots1305 are on the circumference of the firstjoint disk1302. A portion of thefirst tooth slot1510 can extent into one of thefirst alignment slots1305.

The firstjoint disk1302 can include thefirst cable holes1502 arranged around the firstinner opening1322. Thefirst cable holes1502 can have a beveled edge on the bottom of the firstjoint disk1302.

Referring now toFIG. 19A, therein is shown a first isometric view of thesnake wrist structure110 in a fourth embodiment. Thesnake wrist structure110 can include a firstjoint disk1902, a secondjoint disk1932, and a firstinner interlock structure1961.

Thesnake wrist structure110 can include the firstinner interlock structure1961 around the inside diameter of the firstinner opening1922. The firstinner interlock structure1961 can includefirst interlock ribs1981 andfirst interlock slots1982 extending below the bottom of the firstjoint disk1902.

Thesnake wrist structure110 can include a secondinner interlock structure1963. The secondinner interlock structure1963 can include a set ofsecond interlock ribs1983 and a set ofsecond interlock slots1984 extending below the bottom of the secondjoint disk1932.

For example, the firstinner interlock structure1961 can be used to attach to another disk element or to a mounting structure. Thefirst interlock ribs1981 can connect to the complementary interlock slots of another element to hold the firstjoint disk1902 in a fixed orientation to the other disk element or mounting structure.

The firstjoint disk1902 hasfirst alignment keys1906 around the bottom of the circumference of the firstjoint disk1902. Thefirst alignment keys1906 are distributed 90 degrees apart from one another around the bottom circumference of the firstjoint disk1902. Thefirst alignment keys1906 are defined as structures for connecting the firstjoint disk1902 with another disk in a fixed orientation and to prevent rotation of the firstjoint disk1902 relative to another disk.

The firstjoint disk1902 can include afirst tooth slot1910 on afirst rim1971 of the firstjoint disk1902. Thefirst tooth slot1910 can be a concave opening in thefirst rim1971 of the firstjoint disk1902.

The firstjoint disk1902 can include a firsttoothed gear1912 on the opposite side of thefirst rim1971 across from thefirst tooth slot1910. The firsttoothed gear1912 can be a single toothed gear extending from thefirst rim1971 of the firstjoint disk1902.

The firstjoint disk1902 can include a firstangled surface1908 around both sides thefirst rim1971 of the firstjoint disk1902 between the firsttoothed gear1912 to thefirst tooth slot1910. The firstangled surface1908 extends in downward directions from the base of the firsttoothed gear1912 and top of thefirst tooth slot1910 reaching a maximum depth midway between the firsttoothed gear1912 and thefirst tooth slot1910. The firstangled surface1908 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119 ofFIG. 1.

Thefirst rim1971 is defined as a structural element around the circumference of the top of the firstjoint disk1902. Thefirst rim1971 can include thefirst tooth slot1910 and the firstangled surface1908.

Thesnake wrist structure110 can include the secondjoint disk1932. The secondjoint disk1932 can have the same configuration as the firstjoint disk1902. The secondjoint disk1932 is mounted over the firstjoint disk1902 in an inverted position and rotated 180 degrees.

The secondjoint disk1932 can include a secondtoothed gear1942. The secondjoint disk1932 is mounted over the firstjoint disk1902 whereby the secondtoothed gear1942 is over thefirst tooth slot1910 of the firstjoint disk1902. The secondtoothed gear1942 can be inserted into thefirst tooth slot1910 of the firstjoint disk1902.

The secondjoint disk1932 can include a set ofsecond alignment keys1936. Thesecond alignment keys1936 are on the side of the secondjoint disk1932 opposite from the secondtoothed gear1942.

The secondjoint disk1932 can include a secondangled surface1938 around both sides of asecond rim1973 of the secondjoint disk1932 between the secondtoothed gear1942 and a point opposite the secondtoothed gear1942. The secondangled surface1938 extends in a semi-circular arc in an downward direction from the base of the secondtoothed gear1942 and the point opposite the secondtoothed gear1942 reaching a maximum height midway between the secondtoothed gear1942 and a point opposite the secondtoothed gear1942. The secondangled surface1938 is formed at an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

Thesnake wrist structure110 can include ajoint knuckle1995. Thejoint knuckle1995 is formed by connecting the firstjoint disk1902 to the second joint disk. Thejoint knuckle1995 can have an interconnect structure on the proximal and distal ends to facilitate connecting to a further member such as a joint knuckle, instrument, mounting member, or a combination thereof.

Thesnake wrist structure110 has a firsttransverse dimension1996 and a secondtransverse dimension1998 along a plane orthogonal to thecentral axis119 ofFIG. 1. The firsttransverse dimension1996 and the secondtransverse dimension1998 are shown to be the same but do not need to be and may be adjusted based on the geometry of thesnake wrist structure110. In the case in which they are equal, thesnake wrist structure110 may be circular in cross section as illustrated inFIG. 19A. As an example, the firsttransverse dimension1996 and the secondtransverse dimension1998 are shown to be along directions perpendicular to each other but does not necessarily required to be perpendicular.

It has been discovered that the firstangled surface1908 and the secondangled surface1938 can be used to limit the degree of flex in thesnake wrist structure110 without further device or limiting mechanism. The angle formed by the firstangled surface1908 and the secondangled surface1938 thus eliminates external limiters, such as gear mechanisms or strut, and internal limitation features such as bumps, spacers, stoppers, tabs, or a combination thereof, and simplify manufacturing complexity and reduce manufacturing costs.

The secondjoint disk1932 can be coupled to the firstjoint disk1902 by afirst strut1926 and asecond strut1928. Thefirst strut1926 can be a connecting joint structure having afirst hole bearing1927 and afirst slot bearing1925. Thefirst strut1926 can attach to the secondjoint disk1932 with thefirst hole bearing1927 inserted into asecond bearing hole1954. Thefirst strut1926 can attach to the firstjoint disk1902 with the first slot bearing1925 inserted into thefirst tooth slot1910.

The secondtoothed gear1942 of the secondjoint disk1932 remains partially in thefirst tooth slot1910 of the firstjoint disk1902 as thesnake wrist structure110 is flexed. In the flexed position, the tip of the secondtoothed gear1942 is within thefirst tooth slot1910. As the secondjoint disk1932 is unflexed, the shape of the secondtoothed gear1942 allows the secondtoothed gear1942 to slide back into thefirst tooth slot1910 as the secondjoint disk1932 returns to a non-flexed position. The secondtoothed gear1942 and thefirst tooth slot1910 act together to align the firstjoint disk1902 and the secondjoint disk1932 during flexing of thesnake wrist structure110.

It has been discovered that the position and shape of the secondtoothed gear1942 in thefirst tooth slot1910 can align the firstjoint disk1902 and the secondjoint disk1932 during the flexing of thesnake wrist structure110 and reduce the forces on thefirst strut1926. When the stress on thefirst strut1926 is reduced, it can prevent thefirst strut1926 from and causing excessive friction and wear of thefirst strut1926.

Thesnake wrist structure110 can flex in a variety of ways with different degrees of freedom. For example, when the secondjoint disk1932 is flexed toward one side of thesnake wrist structure110, the angular degree of flex is limited by the geometry of the firstangled surface1908 and the secondangled surface1938. The secondjoint disk1932 can only flex a maximum of 45 degrees if when the firstangled surface1908 and the secondangled surface1938 each form a 22.5 degree angle from the horizontal plane. The range of motion of the secondjoint disk1932 is limited by when the firstangled surface1908 and the secondangled surface1938 meet and prevent further motion.

The firstjoint disk1902 and the secondjoint disk1932 can all have the same configuration. For example, the secondjoint disk1932 can be identical versions of the firstjoint disk1902.

It has been discovered that having the firstjoint disk1902 and the secondjoint disk1932 with the same configuration can simplify the manufacture of thesnake wrist structure110 by reducing the number of unique parts required for assembly. Reducing the number of parts can simplify manufacturing complexity and reduce manufacturing cost.

The secondtoothed gear1942 and thefirst tooth slot1910 form a rolling joint1952 between the firstjoint disk1902 and the secondjoint disk1932. The rolling joint1952 is defined as a structure that forms a multi-axis joint between two elements having multiple degrees of freedom. The rolling joint1952 can be the structure where the firstjoint disk1902 and the secondjoint disk1932 join to create a rolling motion where the path of the secondjoint disk1932 with respect to firstjoint disk1902 is defined as the same path as that of the centroid of one circle rolling on the circumference of an identical circle where each circle has a diameter equal to the distance between thefirst slot bearing1925 and thefirst hole bearing1927.

As thesnake wrist structure110 is flexed, the secondjoint disk1932 pivots around the secondtoothed gear1942 and thefirst tooth slot1910. The secondtoothed gear1942 couples with thefirst tooth slot1910 to provide a constraint with an involute profile on the shape of the secondtoothed gear1942 enforcing the rolling motion of the joint. The involute profile of the tooth is defined by the path traced by a point on the circumference of a circle rolling on an identical circle where each circle has a diameter equal to the distance between thefirst slot bearing1925 and thefirst hole bearing1927.

Thefirst strut1926 and thesecond strut1928 lock the firstjoint disk1902 and the secondjoint disk1932 together. Locking is defined as holding two elements together in the same relative position and orientation while still allowing the intended rolling motion of the joint. For example, the locking means the firstjoint disk1902 and the secondjoint disk1932 cannot shift laterally or separate axially, but are still free to pivot. The centroids of the firstjoint disk1902 and the secondjoint disk1932 maintain the same relative position with respect to each other as one disk pivots with respect to another. Locking can hold the firstjoint disk1902 and the secondjoint disk1932 in fixed relative positions to one another even in the absence or failure of joint control cables.

It has been discovered that the present invention provides themedical instrument100 with improved physical integrity by doubling the mechanisms holding thesnake wrist structure110 together. The physical integrity of thesnake wrist structure110 is increased 100% in terms of preventing accidental disassembly and loss of components during operation. Thefirst strut1926 locks the firstjoint disk1902 and the secondjoint disk1932 together without external connection structures, such as joint control cables or central lumen cables. Locking the firstjoint disk1902 and the secondjoint disk1932 together can prevent the loss of components of thesnake wrist structure110 in case elements such as the joint control cables are damaged or broken. Preventing the loss of components makes thesnake wrist structure110 safer by reducing the likelihood of a component being lost within a patient during surgery.

It has been discovered that the present invention provides themedical instrument100 with improved reliability of operation. The use of the secondtoothed gear1942 in thefirst tooth slot1910 supports the maintaining of constant length cabling in thesnake wrist structure110. Constant length cabling is defined as a cabling configuration where the cables maintain a constant length. Constant length cabling can insure that as a cable is pulled out of one side of a joint, the opposite side will take up an equal amount of cable.

Referring now toFIG. 19B, therein is shown a second isometric view of thesnake wrist structure110 in a fourth embodiment. Thesnake wrist structure110 can include the firstjoint disk1902, the secondjoint disk1932, aflex axis1950, and asnake wrist lumen1993.

The firstjoint disk1902 and the secondjoint disk1932 form a joint that can flex around theflex axis1950. Theflex axis1950 is defined as the effective axis as the firstjoint disk1902 and the secondjoint disk1932 rotate around the connection formed by thefirst strut1926 and thesecond strut1928.

The firstjoint disk1902 can be a joint structure element that can be coupled to other similar disks to form thesnake wrist structure110 having a firstinner opening1922 in the center of the firstjoint disk1902. The firstinner opening1922 is defined as the central unobstructed through lumen of the firstjoint disk1902. A lumen is defined as an internal cavity or opening in a cylindrical structure. The inner openings of the coupled disks of thesnake wrist structure110 form thesnake wrist lumen1993 in thesnake wrist structure110.

Thesnake wrist lumen1993 is defined as a channel in thesnake wrist structure110 that can be used to pass mechanical, electrical, or optical cables or other control tubes. Thesnake wrist lumen1993 can also be a through lumen for providing fluid or gas delivery or extraction, or for use as a through lumen in the instrument to allow for the passage of secondary smaller diameter surgical tools through the snake joint assembly such as a biopsy needle, grasper, or laser fiber.

Referring now toFIG. 20 therein is shown an isometric of thesnake wrist structure110 in a flexed position in a fourth embodiment. Thesnake wrist structure110 can include the firstjoint disk1902, the secondjoint disk1932, the firstinner interlock structure1961, and the secondinner interlock structure1963.

Thesnake wrist structure110 can include the firstinner interlock structure1961 around the inside diameter of the firstinner opening1922. The firstinner interlock structure1961 can includefirst interlock ribs1981 andfirst interlock slots1982 extending below the bottom of the firstjoint disk1902.

Thesnake wrist structure110 can include the secondinner interlock structure1963 around the inside diameter of a secondinner opening2051. The secondinner interlock structure1963 can include a set ofsecond interlock ribs1983 and a set ofsecond interlock slots1984 extending below the bottom of the secondjoint disk1932.

The firstjoint disk1902 hasfirst alignment keys1906 around the bottom of the circumference of the firstjoint disk1902. Thefirst alignment keys1906 are distributed 90 degrees apart from one another around the bottom circumference of the firstjoint disk1902. Thefirst alignment keys1906 can be connected to the alignment keys of another disk

The firstjoint disk1902 can include thefirst tooth slot1910 on thefirst rim1971 of the firstjoint disk1902. The firstjoint disk1902 can include the firsttoothed gear1912 on the opposite side of thefirst rim1971 across from thefirst tooth slot1910.

The firstjoint disk1902 can include the firstangled surface1908 around both sides thefirst rim1971 of the firstjoint disk1902 between the firsttoothed gear1912 to thefirst tooth slot1910. The firstangled surface1908 extends in downward directions from the base of the firsttoothed gear1912 and top of thefirst tooth slot1910 reaching a maximum depth midway between the firsttoothed gear1912 and thefirst tooth slot1910. The firstangled surface1908 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119.

Thesnake wrist structure110 can include the secondjoint disk1932. The secondjoint disk1932 can have the same configuration as the firstjoint disk1902. The secondjoint disk1932 is mounted over the firstjoint disk1902 in an inverted position and rotated 180 degrees.

The secondjoint disk1932 can include the secondtoothed gear1942. The secondjoint disk1932 is mounted over the firstjoint disk1902 whereby the secondtoothed gear1942 is over thefirst tooth slot1910 of the firstjoint disk1902. The secondtoothed gear1942 can be inserted into thefirst tooth slot1910 of the firstjoint disk1902.

The secondjoint disk1932 can include thesecond alignment keys1936. Thesecond alignment keys1936 are on the side of the secondjoint disk1932 opposite from the secondtoothed gear1942 and facing away from the firstjoint disk1902.

The secondjoint disk1932 can include the secondangled surface1938 around both sides of thesecond rim1973 ofFIG. 19A of the secondjoint disk1932 between the secondtoothed gear1942 to point opposite the secondtoothed gear1942. The secondangled surface1938 extends in a semi-circular arc in an downward direction from the base of the secondtoothed gear1942 reaching a maximum height midway between the secondtoothed gear1942 and a point opposite from the secondtoothed gear1942. The secondangled surface1938 is formed an angle of 22.5 degrees below a plane orthogonal to thecentral axis119 ofFIG. 1.

The secondjoint disk1932 can be coupled to the firstjoint disk1902 by afirst strut1926 and thesecond strut1928. Thefirst strut1926 can be a connecting joint structure having afirst hole bearing1927 and afirst slot bearing1925.

Thefirst strut1926 can attach to the secondjoint disk1932 with thefirst hole bearing1927 inserted into thesecond bearing hole1954. Thefirst strut1926 can attach to the firstjoint disk1902 with the first slot bearing1925 inserted into thefirst tooth slot1910.

The secondjoint disk1932 can include thesecond alignment keys1936 around the bottom of the circumference of the secondjoint disk1932. For example, thesecond alignment keys1936 are distributed 90 degrees apart from one another around the bottom circumference of the firstjoint disk1902. Thefirst alignment keys1906 can be connected to the alignment keys of another element.

The secondjoint disk1932 can be in a flexed position where the secondjoint disk1932 is flexed around the bearing axis and the secondangled surface1938 is closer to the firstangled surface1908 on one side of thesnake wrist structure110 and further apart on the opposite side of thesnake wrist structure110.

Referring now toFIG. 21 therein is shown an exploded view of the snake wrist structure in a fourth embodiment. Thesnake wrist structure110 includes a firstjoint disk1902, the secondjoint disk1932, afirst strut1926, thesecond strut1928, a third joint disk, a firstinner interlock structure1961, the secondinner interlock structure1963, thesnake wrist lumen1993 ofFIG. 19B, and a thirdinner interlock structure2102.

The firstjoint disk1902 can include thefirst alignment keys1906, the firstangled surface1908, thefirst tooth slot1910, and the firsttoothed gear1912. The firstjoint disk1902 can include the firstinner interlock structure1961.

The secondjoint disk1932 is over the firstjoint disk1902. The secondjoint disk1932 can include thesecond alignment keys1936, the secondangled surface1938, the secondtoothed gear1942, and a set of second cable holes1933. The secondjoint disk1932 can include the secondinner interlock structure1963.

Thefirst strut1926 can be connected between the firstjoint disk1902 and the secondjoint disk1932. Thefirst strut1926 can include thefirst hole bearing1927, thefirst slot bearing1925, and thefirst connection link2110.

Thesecond strut1928 can be connected between the firstjoint disk1902 and the secondjoint disk1932. Thesecond strut1928 can include a second hole bearing2127, a second slot bearing2147, and asecond connection link2120. Thesecond strut1928 can have the same configuration as thefirst strut1926 rotated 180 degrees in the vertical direction.

A thirdjoint disk1962 is over the secondjoint disk1932. The thirdjoint disk1962 can include a set ofthird alignment keys2106, a thirdangled surface2185, athird tooth slot1970, a thirdtoothed gear1972. The thirdjoint disk1962 can include the thirdinner interlock structure2102.

Thefirst strut1926 includes thefirst slot bearing1925 and thefirst hole bearing1927 connected by thefirst connection link2110. Thefirst strut1926 can support three axes of rotation. The firstjoint disk1902 can rotate around thefirst slot bearing1925. The secondjoint disk1932 can rotate around thefirst hole bearing1927. Thefirst slot bearing1925 and thefirst hole bearing1927 can rotate relative to each other and thefirst connection link2110.

The first slot bearing1925 can include a firstslot bearing surface2111. Thefirst hole bearing1927 can include a firsthole bearing surface2115. Because thefirst strut1926 has two bearings, thefirst slot bearing1925 and thefirst hole bearing1927, thefirst strut1926 can include a large overall bearing surface area and a higher load capacity. Thus, thefirst strut1926 with two bearings can be smaller than a strut with only one bearing for the same load capacity. This allows the overall physical dimensions of thefirst strut1926 to be reduced.

It has been discovered that the present invention provides themedical instrument100 with a larger cable payload in thesnake wrist lumen1993 because thesnake wrist lumen1993 can be larger. Providing thefirst strut1926 with two bearings, thefirst slot bearing1925 and thefirst hole bearing1927, reduces the overall size of each bearing by 50% over that needed to support the same load with a single bearing joint. Thefirst strut1926 can be of smaller size in terms of bearing diameter, bearing width, or a combination thereof. The smaller version of thefirst strut1926 can be used in thesnake wrist structure110 with a thinnerfirst rim1971 resulting in an increased diameter of thesnake wrist lumen1390. If thesnake wrist lumen1993 is larger, the amount of cables and payload in thesnake wrist lumen1993 can be increased to provide additional capability for thesnake wrist structure110.

The firsttoothed gear1912 can include a firsttoothed gear coating2139 on the surface of the firsttoothed gear1912 to reduce friction between the firstjoint disk1902 and the secondjoint disk1932. The firsttoothed gear coating2139 is defined as a wear resistant material over the surface of the firsttoothed gear1912. For example, the firsttoothed gear1912 can be manufactured of a variety of medical grade metal alloys. The medical grade metal alloys composition can include Nitronic 60, surgical stainless steel, titanium, nickel, chromium, molybdenum, or a combination thereof. The firsttoothed gear1912 can include a wear-resistant coating on the tooth to prevent galling and wear. The firsttoothed gear coating2139 can be a variety of medical grade wear-resistant coatings such as diamond-like carbon, thin dense chromium, fluropolymer, or Medcoat 2000.

It has been discovered that the present invention provides themedical instrument100 with improved durability and wear resistance. Including a firsttoothed gear coating2139 on the surface of the firsttoothed gear1912 can prevent galling and wear on thefirst strut1926, leading to an extended operational life of thesnake wrist structure110. The wear-resistant coating can reduce friction between the firstjoint disk1902 and the secondjoint disk1932 resulting in less wear that can allow the use of softer materials in the manufacture of thefirst strut1926.

Referring now toFIG. 22 therein is shown an isometric view of the bottom of the firstjoint disk1902 in a fourth embodiment. The firstjoint disk1902 can include thefirst cable holes1914, thefirst alignment keys1906, and the firstinner interlock structure1961.

The firstjoint disk1902 can include an interlocking structure on the bottom of the firstjoint disk1902 for connecting the firstjoint disk1902 to another disk element or other mounting structure. The interlocking structure can hold the firstjoint disk1902 and another disk element in a fixed orientation. The interlocking structure can include a variety of mating structures including thefirst alignment keys1906 with an firstalignment key tab2203 and the first alignmentkey hole2205, a rib and slot structure, a pin and hole structure, a grooved structure, or a combination thereof.

For example, thefirst alignment keys1906 are four interlocking structures positioned at 90 degree intervals around the bottom of the firstjoint disk1902. One of thefirst alignment keys1906 is under thefirst tooth slot1910. One of thefirst alignment keys1906 is opposite thefirst tooth slot1910 and under the firsttoothed gear1912. The other twofirst alignment keys1906 are under the lowest points of the firstangled surface1908.

The firstjoint disk1902 can include thefirst cable holes1914 arranged around the firstinner opening1922. Thefirst cable holes1914 are arranged between thefirst alignment keys1906 and evenly distributed between each adjacent pair of thefirst alignment keys1906. Thefirst cable holes1914 can have a beveled edge on the bottom of the firstjoint disk1902.

The firstjoint disk1902 can include the firstinner interlock structure1961. The firstinner interlock structure1961 can include the firstinner interlock ribs2207 and firstinner interlock slots2209.

The firstjoint disk1902 can include the firstinner opening1922. The firstinner opening1922 is an opening in acentral portion2202 of the firstjoint disk1902. Thecentral portion2202 is defined as the interior part of the firstjoint disk1902 surrounding thecentral axis119 ofFIG. 1.

Referring now toFIG. 23 therein is shown a side and front view of thefirst strut1926. Thefirst strut1926 can include thefirst slot bearing1925, thefirst connection link2110, and thefirst hole bearing1927.

Thefirst slot bearing1925 is roughly cylindrical. Thefirst strut1926 can include afirst landing surface2319 facing thefirst hole bearing1927. Thefirst landing surface2319 can include a flat surface facing thefirst hole bearing1927. The first slot bearing1925 can include afirst locking lip2306 on the outer edge of the first slot bearing1925 on the side facing away from thefirst hole bearing1927.

Thefirst strut1926 can include a firstslot locking notch2308 on the inner edge of thefirst slot bearing1925. The first slot bearing1925 can include a firstslot bearing surface2111 on the side of the first slot bearing1925 facing away from thefirst hole bearing1927.

Thefirst strut1926 can include thefirst connection link2110 between thefirst slot bearing1925 and thefirst hole bearing1927. Thefirst connection link2110 is directly connected to thefirst slot bearing1925 and thefirst hole bearing1927.

Thefirst hole bearing1927 is roughly cylindrical. Thefirst strut1926 can include a firsthole locking notch2303 on the inner edge of thefirst hole bearing1927. Thefirst hole bearing1927 can include a firsthole bearing surface2115 on the side of thefirst hole bearing1927 facing away from thefirst slot bearing1925.

Thesnake wrist structure110 ofFIG. 1 can be in a variety of configurations. For example, thesnake wrist structure110 can be placed under stress during operation. In one scenario, 12 joint control cables can exert a force of 160 Newtons per joint control cable for a total force of 1920 Newtons. Estimating a one half load on each strut, gives 960 Newtons per strut. Given perfirst strut1926 where the bearing surfaces of the bearings are A_b1=2.1947 mm²and A_b2=1.716123 mm²

For example, thesnake wrist structure110 can include a configuration where the snake wrist structure consisting of repeating identical single-degree of freedom joints connected in series with joint axes orthogonal to the central axis of the instrument shaft and either parallel or orthogonal to adjacent identical single-degree of freedom joints as dictated by the desired degrees of freedom and range of motion of the snake wrist structure. The repeating single-degree of freedom joint structure includes: a first joint disk having a first rim having a first tooth slot and a first toothed gear with the first tooth slot opposite the first toothed gear along the first rim; and a first strut having a first slot bearing and a first hole bearing connected by a first connection link with the first slot bearing in the first tooth slot, whereby an articulated joint is formed by connecting two pairs of first joint disk and first struts together with a 180 degree relative orientation to one another and locking said combination of first joint disks and first struts together by mating additional repeating single degree of freedom joints in series

Referring now toFIG. 24 therein is shown an isometric view of the firstjoint disk1902 in a fourth embodiment. The firstjoint disk1902 can include thefirst alignment keys1906, the firstangled surface1908, the firsttoothed gear1912, thefirst tooth slot1910, thefirst rim1971, the firstinner opening1922, thefirst cable holes1914, thefirst cable cutouts2416, and the firstinner interlock slots2209.

The firstjoint disk1902 can include a firstinner ring2402, thefirst bearing hole2404, thefirst bearing slot2406, a firstbearing mounting hole2408. The firstinner ring2402 is defined as a raised structural element of the firstjoint disk1902 around and forming the firstinner opening1922. The firstinner ring2402 can be a raised ridge between thefirst cable holes1914 and the firstinner opening1922.

Thefirst bearing slot2406 is defined as a structural element for supporting the inner side of the first slot bearing1925 ofFIG. 19. Thefirst bearing slot2406 can be a concave opening in the firstinner ring2402. Thefirst bearing slot2406 is adjacent to the firsttoothed gear1912.

The firstbearing mounting hole2408 is defined as a structural element for supporting the inner side of the second hole bearing2127 ofFIG. 21. The firstbearing mounting hole2408 can be an hole in the firstinner ring2402. The firstbearing mounting hole2408 is adjacent to thefirst tooth slot1910.

The firstjoint disk1902 can include the firsttoothed gear1912 on thefirst rim1971. Thefirst bearing hole2404 is directly below the firsttoothed gear1912 between the firsttoothed gear1912 and one of thefirst alignment keys1906 on the bottom side of the firstjoint disk1902. Afirst bearing slot2406 is on the firstinner ring2402 on the same side as the firsttoothed gear1912.

The firstjoint disk1902 can include thefirst tooth slot1910 on thefirst rim1971 opposite from the firsttoothed gear1912. The firstjoint disk1902 can include the firstbearing mounting hole2408 on the firstinner ring2402 on the same side as thefirst tooth slot1910.

The firstjoint disk1902 can include thefirst cable holes1914 and thefirst cable cutouts2416 between thefirst rim1971 and the firstinner ring2402. The firstinner ring2402 is around the firstinner opening1922. The firstinner opening1922 is between thefirst bearing slot2406 and the firstbearing mounting hole2408.

It has been discovered that the present invention thus has numerous aspects.

A principle aspect that has been unexpectedly discovered is that the present invention can provide a simplified mechanism for forming a snake wrist structure for medical instruments. Embodiments of the present invention have been found to reduce the number of parts required for the snake wrist structure to a joint disk, a locking element, and a strut.

Another aspect is the present invention utilizes only standard assembly processes, yet is extremely reliable. The finished snake wrist structure can be made with a smaller diameter and no additional space is required to implement the present invention.

The resulting method, process, apparatus, device, product, and/or system is straightforward, cost-effective, uncomplicated, highly versatile, accurate, sensitive, and effective, and can be implemented by adapting known materials and processes for ready, efficient, and economical manufacturing, application, and utilization.

Another important aspect of the present invention is that it valuably supports and services the historical trend of reducing costs, simplifying systems, and increasing performance.

These and other valuable aspects of the present invention consequently further the state of the technology to at least the next level.

While the invention has been described in conjunction with a specific best mode, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the included claims. All matters hithertofore set forth herein or shown in the accompanying drawings are to be interpreted in an illustrative and non-limiting sense.

Claims (20)

What is claimed is:

1. A medical instrument comprising:

a first joint disk including a first rim having a first tooth slot and a first toothed gear, the first tooth slot being opposite the first toothed gear along the first rim; and

a first strut having a first slot bearing and a first hole bearing connected by a first connection link with the first slot bearing in the first tooth slot,

the first tooth slot being shaped to contain the first slot bearing and at least a portion of a second toothed gear.

2. The instrument as claimed inclaim 1 wherein:

the first hole bearing includes a first hole locking notch; and

the first slot bearing includes a first slot locking notch.

3. The instrument as claimed inclaim 1 wherein:

the first joint disk includes first cable holes and includes first cable cutouts around the first cable holes.

4. The instrument as claimed inclaim 1 wherein:

the first joint disk includes a first inner ring around a central portion having a first inner opening;

the first inner ring has a first bearing mounting hole adjacent to the first tooth slot; and

the instrument further comprises a set of first cable holes between the first inner ring and the first rim.

5. The instrument as claimed inclaim 1 wherein:

the first joint disk has a first inner opening; and

the instrument further comprises a first inner interlock structure around the inside circumference of the first inner opening, the first interlock structure having interlock ribs and interlock slots.

6. A medical instrument comprising:

a first joint disk including a first rim having a first tooth slot and a first toothed gear, the first tooth slot being opposite the first toothed gear along the first rim;

a first strut having a first slot bearing and a first hole bearing connected by a first connection link with the first slot bearing in the first tooth slot; and

a first angled surface extending along the first rim between the first toothed gear and the first tooth slot, the first angled surface forming a cut-out angle relative to a plane orthogonal to a central axis of the first joint disk.

7. The instrument as claimed inclaim 6 wherein:

the first strut includes a first slot locking notch on the inner edge of the first slot bearing; and

the instrument further comprises a first locking member in direct contact with the first joint disk and the first slot locking notch, the first locking member being positioned to lock the first strut to prevent lateral movement.

8. The instrument as claimed inclaim 6 wherein:

the first joint disk has first alignment ribs and first alignment slots around a circumference of a bottom of the first joint disk.

9. The instrument as claimed inclaim 6 wherein:

the first angled surface forms a cut-out angle of 22.5 degrees below a plane orthogonal to a central axis of the first joint disk.

10. The instrument as claimed inclaim 6 wherein:

the first angled surface extends around a circumference of the first rim, between the first tooth slot and the first toothed gear.

11. A medical instrument including a snake wrist structure comprising:

a first joint disk including a first rim having a first tooth slot and a first toothed gear, the first tooth slot being opposite the first toothed gear along the first rim;

a first strut having a first slot bearing and a first hole bearing connected by a first connection link, the first slot bearing being in the first tooth slot;

a second joint disk including a second rim having a second tooth slot and a second toothed gear, the second tooth slot being opposite the first toothed gear along the second rim; and

a second strut having a second slot bearing and a second hole bearing connected by a second connection link, the second slot bearing being in a second tooth slot.

12. The instrument as claimed inclaim 11 wherein:

the second joint disk is mounted over the first joint disk;

the first toothed gear is in the second tooth slot; and

the second toothed gear is in the first tooth slot.

13. The instrument as claimed inclaim 11 wherein:

the first strut and the second strut are connected between the first joint disk and the second joint disk;

the first joint disk has a first bearing hole adjacent to the first toothed gear, the second hole bearing being in the first bearing hole; and

the second joint disk has a second bearing hole adjacent to the second toothed gear, the first hole bearing being in the second bearing hole.

14. The instrument as claimed inclaim 11 wherein:

the second toothed gear is within the first tooth slot and is positioned to align the second joint disk with the first joint disk.

15. The instrument as claimed inclaim 11 wherein:

the first strut, the second toothed gear, and the first tooth slot form a rolling joint between the first joint disk and the second joint disk.

16. The instrument as claimed inclaim 11 further comprising:

a first angled surface extending along the first rim between the first toothed gear and the first tooth slot; and

a second angled surface extending along the second rim between the second toothed gear and the second tooth slot.

17. The instrument as claimed inclaim 16 wherein:

the first toothed gear includes a first toothed gear coating on the surface of the first toothed gear, the first toothed gear coating being positioned to prevent galling.

18. The instrument as claimed inclaim 16 further comprising:

a third joint disk having third alignment ribs and third alignment slots around a circumference of the third joint disk; wherein:

the second joint disk has second alignment ribs and second alignment slots around a circumference of the second joint disk in direct contact with the third joint disk.

19. The instrument as claimed inclaim 16 wherein:

connection of the first joint disk to the second joint disk provides a first flex axis perpendicular to a central axis of the first joint disk; and

the instrument further comprises a third joint disk connected to the second joint disk and rotated 90 degrees around the central axis to provide a second flex axis that is orthogonal to the first flex axis.

20. The instrument as claimed inclaim 16 further comprising:

a central portion of the first joint disk having a first inner opening; and

a first inner interlock structure around the inside diameter of the first inner opening.

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